Opossums. 



MUSEUM OF ANIMATED NATURE. 



23 



greyish black ; the palate flesh-coloured ; the under 

 mandible paler externally. The edges of both are 

 soft, and the lower, which is the shortest and nar- 

 rowest of the two, has its edge adapted to a depres- 

 sion under the margin of the upper mandible, which 

 is also channelled with obliquely transverse furrows, 

 those however are merely in the leathery skin. 

 There are no horny lamime as in the bill of the 

 duck. True teeth are wanting ; but on each side in 

 either mandible there are two horny appendages 

 without roots ; one on each side is large and tuber- 

 culous, situated on the base of the mandibles, at the 

 posterior part of the mouth ; the other forms a long 

 narrow ridge on the anterior part of the mandible 

 along the "edge (see fig. 98). Capacious cheek- 

 pouches are carried under the skin of the face, from 

 the inside of the mouth, serving as receptacles for 

 food. At the base of the beak, separating between it 

 and the head, there projects abroad loose leathery 

 flap from each mandible, the use of which is probably 

 to defend the eyes and fur of the head from the 

 mud in which the animal grubs, duck-like, in quest 

 of insects. The tongue is short and thick, and 

 covered with long papillae. The nostrils are two 

 small orifices situated near the apex of the upper 

 mandible. The eyes are small, but brilliant, and 

 placed rather high in the head. The ears open ex- 

 ternally by a simple orifice near the external angle 

 of the eyes, and are capable of being expanded or 

 closed at pleasure. 



The fore feet are largely webbed and divided into 

 five toes, terminating in strong blunt, burrowing 

 claws. The web which unites the toes is tough and 

 leathery : it extends considerably beyond the claws, 

 and would appear at first sight to act as an impedi- 

 ment to the animal while excavating its long bur- 

 row. We do not find, however, that this is the 

 ease : it can be folded back at pleasure. The hind 

 feet are smaller and less powerful than the anterior 

 pair : they are divided into five toes armed with 

 sharp claws and webbed, but the membrane is 

 not carried out beyond the roots of the claws. The 

 hind feet are directed backwards as in those of the 

 seal (see skeleton, fig. 99), and their action is 

 backwards and outwards. The tarsus of the male 

 is armed with a large sharp moveable spur turned 

 backwards and inwards. It is not used as a weapon 

 of defence, nor are accidental wounds and scratches 

 made by it while struggling in a person's hands 

 attended with ill effects. Formerly this spur was 

 regarded as poisonous. In the female a rudimen- 

 tary spur may be distinguished (see fig. 100). 



The body is elongated, low, and depressed ; the 

 fur is close and fine, and consists of two sorts, an 

 under-layer of soft, short, waterproof wadding, and 

 an outer vest of long fine glossy hair, thickly set, 

 and in many instances assuming a crisped appear- 

 ance. The tail is strong, broad, flattened, and of 

 moderate length : it is covered above with longer 

 and coarser hairs than those of the body, but its 

 under surface is only scantily furnished. General 

 colour deep brown; head and under parts paler; 

 a whitish spot in front of each eye ; average length 

 of head and body, including tail, twenty to twenty- 

 three inches ; beak, about two inches and a half; 

 tail, four or five inches. 



Essentially aquatic, as is sufficiently declared by 

 its outward structure, the Ornithorhynchus passes 

 the active part of its existence almost exclusively 

 in the water. The favourite places of resort of 

 this animal are tranquil parts of rivers with high 

 steep banks, and abounding in waterweeds, among 

 which, and in the oozy mud, are the insects, &c. on 

 which it feeds. 



Their burrows (see fig. 101) are excavated in 

 the steep banks overhanging the tranquil sheets of 

 water in which they seek their food. These bur- 

 rows are continued in a serpentine form, rising as 

 they proceed, the termination often being at the 

 distance of fifty feet from the mouth. The entrance 

 is generally larger than the rest of the passage, but 

 the termination is again enlarged, so as to be com- 

 modious for the parents and their offspring. The 

 female produces from two to four at a birth, and in 

 the month of November (a summer month in Aus- 

 tralia). The young at an early period (immediately 

 after birth, and for some time afterwards) are naked 

 and very small, and their general aspect is very 

 unlike that of the fully developed animal. They 

 are curled round, the head and tail being doubled 

 on the abdomen ; the skin of the body is thrown 

 into transverse folds ; the eyes are merely indicated 

 by the convergence of a few wrinkles on the skin, 

 which passes over these organs, proving that their 

 development does not take place till a considerable 

 time after birth, and, together with the helpless 

 rudimentary condition of the young animal, demon- 

 strating that it is necessarily confined for a long 

 period to the nest in which it is brought forth, 

 and consequently that it does not and cannot follow, 

 as has been conjectured, like a duckling just hatched, 

 its parents to the water. The beak is small, soft, 

 and covered with thin skin, '*The margins of the 



upper mandibl , are rounded, smooth, tniclc, and 

 fleshy ; the whole of the under mandible is flexible, 

 and bends down upon the neck when the mouth is 

 attempted to be opened. The tongue, which in the 

 adult is lodged far back in the mouth, advances in 

 the young "animal close to the end of the lower 

 mandible ; all the increase of the jaws beyond the 

 tip of the tongue, which in the adult gives rise to a 

 form of the mouth so ill calculated for suction or 

 application to a flattened surface, is peculiar to 

 that period, and consequently forms no argument 

 against the fitness of the animal to receive the 

 mammary secretion at an earlier stage of existence." 

 (Prof. Owen.) 



That the Ornithorhynchus suckles its young, and 

 possesses a milk-secreting apparatus, are facts 

 which, though once denied, are now incontestably 

 proved. 



If the hairs be removed from the abdomen of a 

 female Ornithorhynchus, an areola or oval spot, may 

 be distinguished," consisting of a group of ducts, 

 very minute, yet with orifices larger than those in 

 which the hairs are implanted. The areola varies 

 in extent, and the ducts lead to a large glandbe- 

 neath the skin, and a thin muscular expansion. 

 This mammary gland is composed of a number of 

 lobes, amounting from one hundred and twenty to 

 two hundred, and these are the cells in which the 

 milk is secreted, and which oozes from the ducts, 

 and is received by the soft mouth of the young, 

 which is capable of being closely applied to the 

 areola. 



Specimens of two young Ornithorynchi of different 

 sizes were minutely examined by Professor Owen. 

 The smallest of these rather exceeded two inches in 

 length ; the largest was double that size, and was 

 one of the two young ones taken with a mother 

 from -a nest, on the banks of the Fish river, by Lieu- 

 tenant the Honourable Lauderdale Maule, and kept 

 alive for about a fortnight by that gentleman. The 

 stomach of this larger specimen was found to be full 

 of coagulated milk. On carefully inspecting the 

 whole contents with a lens, no portion of worms or 

 bread could be detected, which, Mr. Owen observes, 

 solves the doubt entertained by Lieutenant Maule, 

 as to whether the mother nourished this young one 

 with the food which was given to her for her sup- 

 port, or with the secretion afterwards discovered to 

 escape from the mammary pores; for the mother 

 having been killed by accident on the fourteenth 

 day after her captivity, it was observed, on skinning 

 her while yet warm, that milk oozed through the 

 fur on the stomach. That it was really milk on the 

 stomach of the young animal, Professor Owen de- 

 monstrated, and the matter may be considered as 

 fairly set at rest. Another point, which seems to be 

 now established is that the Ornithorynchus is ovovi- 

 viparous, or, in other words, produces eggs, which, 

 as in the cas§ of the viper, and the viviparous lizard 

 (Zootoca vivipara, Bell), are hatched just before ex- 

 clusion, the young being born rudimentary and 

 naked. 



Referring to our illustrations, fig. 103 exhibits 

 a portion of the integument from the abdomen of 

 the Ornithorhynchus, with the hairs removed, to 

 show the mammary areola. (Owen, ' Phil. Trans.') 

 Fig. 104, a magnified view of the mammary 

 areola, showing the orifices of the ducts of the 

 glandular lobules. Fig. 105 shows the mammary 

 lobular gland of the Ornithorhynchus, reduced be- 

 low the natural size. (Owen, 'Phil. Trans.') Fig. 

 196, view of the larger of the specimens of young 

 Ornithorhynchi alluded to. a, the nostrils; c, the 

 eyes ; d, the ears ; e, the vent. ; /, the orifice and 

 rudimentary spur of the hind foot ; g, membrane at 

 the base of the mandibles. (Owen, ' Zool. Trans.') 

 Fig. 107, smaller specimen of young ornithorhyn- 

 chus, and front view of head, a, nostrils ; b, promi- 

 nence on upper mandibles ; e, vent ; /, orifice and 

 rudimentary spur on hind foot ; c, the eyes ; d, the 

 ears ; g, the membrane at the base of the man- 

 dibles ; k, the tongue. (Owen, ' Zool. Trans.') 



The ratio in which the development of the young 

 Ornithorhynchus proceeds is not ascertained. 



The Ornithorhynchus has never been brought 

 alive to Europe. From the account of Mr. Ben- 

 nett, who procured and kept several in Australia, 

 it appears to be a lively interesting creature. Its 

 voice, which it utters when alarmed or disturbed, 

 resembles the growl of a puppy, but in a softer 

 key. It dresses its fur. and seems to delight in 

 keeping it smooth and clean. (Fig. 96.) The 

 mandibles are endowed with great sensibility. 

 Speaking of a family of these creatures which he 

 obtained, and which lived a considerable time 

 in captivity, Mr. Bennett says " The young 

 sleep in various postures ; sometimes in an ex- 

 tended position, and often rolled up, like a hedge- 

 hog, in the form of a ball. (Fig. 97.) They 

 formed an interesting group, lying in varioiss atti- 

 tudes in the box in which I had placed them, and 

 seeming happy and content. Thus, for instance, 

 one lies curled up like a dog, keeping its back warm 



with the flattened tail, which is brought over it, 

 while the other lies stretched on its back, the head 

 resting, by way of a pillow, on the body of the old 

 one, which lies on its side, with the back resting 

 against the box ; the delicate beak, and smooth 

 clean fur of the young, contrasting with the rougher 

 and dirtier appearance of the older one : all fast 

 asleep." The gambols of the young Ornithorhynchi 

 are thus detailed: "One evening both the animals 

 came out about dusk, and went as usual, and ate 

 food from the saucer, and then commenced playing 

 with one another like two puppies, attacking with 

 their mandibles, and raising their fore-paws against, 

 each other. In the struggle one would get thrust 

 down, and at the moment when the spectator would 

 expect it to rise again and renew the combat, it 

 would commence scratching itself, its antagonist 

 looking on, and waiting for the sport to be renewed. 

 When running they are exceedingly animated ; 

 their little eyes glisten, and the orifices of their ears 

 contract and dilate with rapidity : if taken into the 

 hands at this time for examination, they struggle 

 violently to escape ; and their Joose integuments 

 make it difficult to retain them. Their eyes being 

 placed so high on the head, they do not see objects 

 well in a straight line, and consequently run against 

 everything in the room during their perambula- 

 tions, spreading confusion among all the light and 

 readily-overturnable articles. I have occasionally 

 seen them elevate the head, as if to regard objects 

 above or around them. Sometimes I have been 

 able to enter into play with them by scratching and 

 tickling them with my finger : they seemed to en- 

 joy it exceedingly, opening their mandibles, and 

 bitingplayfullyatthe finger, and moving about like 

 puppies indulged with similar treatment. As well 

 as combing their fur to clean it when wet, I have 

 also seen them peck at it with their beak (if the 

 term may be allowed) as a duck would clean its fea- 

 thers. When I placed them in a pan of deep w r ater, 

 they were eager to get out after being there for 

 only a short time ; but when the water was shallow, 

 with a turf of grass in one corner, they enjoyed it 

 exceedingly. They would sport together, attacking 

 one another with their mandibles, and roll over in 

 the water in the midst of their gambols, and would 

 afterwards retire, when tired, to the turf, where they 

 would lie combing themselves. They appeared to 

 be in a great measure nocturnal, preferring the twi- 

 light to the bright glare of day." 



In fig. 108, the skull of the Ornithorhynchus is 

 represented in different aspects : a, as seen from 

 above ; b, as seen from below ; c, as seen from be- 

 hind. The upper figure is that of the under jaw. 

 The skull is remarkable for the flattened and elon- 

 gated form of the bones of the facial portion ; the 

 intermaxillary bones, which are, as it were, let into 

 projecting maxillaries, diverge, leaving a vast open- 

 ing (the foramen incisivum). The cranial cavity is 

 considerable ; the orbits are small ; the zygomatic 

 arch slender and compressed. The suborbitar 

 foramen appears on the edge of the upper mandible, 

 its situation being marked by a projection of the 

 bone. The lower-jaw is slender and depressed; 

 there are no coronoid processes ; the outer sides of 

 the ascending rami (though very narrow) have, as 

 in most, if, indeed, not all the Marsupials, a pit-like 

 cavity for the lodgment of the masseter muscle. 

 The extent of the temporal muscle is trifling. The 

 skull of the Ornithorhynchus can be confounded 

 with that of no other animal. 



With respect to the sternal apparatus to which 

 we alluded in our account of the Echidna, it appears 

 to be formed more after the model of that of the 

 Saurian reptiles, than after that of Mammalia. (See 

 fig. 102.) 



Fossil Marsupuds. — Besides the fossil opossum 

 of the Montmartre gypsum (Didelphijs Cuvieri), and 

 the fossil Dasyurus, Hypsiprymnus, Halmaturus ; 

 Phascolomys, and Kangaroo, from the Australian 

 bone-caves and breccia, two fossil forms discovered 

 in theStonesfield oolite, as evidenced by portions of 

 the lower jaw, have recently attracted much atten- 

 tion and no little discussion. Some anatomists, with 

 M. de Blainville, contend against the Mammal origin 

 of these relics, or at least of one of the forms ; but 

 those who have examined the fossils and read the 

 arguments on either side, will, we think, agree with 

 Baron Cuvier and Professor Owen, and assign them 

 to animals of the Marsupial section, which at some 

 epoch tenanted our quarter of the globe. The jaws 

 of these extinct Marsupials, named respectively 

 Thylacotherium Prevostii, Owen (fig. 109), and 

 Phascolotherium Bucklandii, Owen (fig. 110), are 

 represented of the natural size, and also magnified, 

 in order to show clearly the characters and arrange- 

 ment of the teeth. Those who wish to enter into 

 the full details respecting these fossil relics will 

 do well to consult the 'Geological Proceedings,' 

 1838-9; Cuvier's 'Ossemens Foss.,' vol. v. ; 'Ann. 

 des Sciences,' 1825 ; and the papers of Mr. Broderip 

 and Dr. Fitton in the ' Zool. Journal,' 1828. 



