MAKSUl'IATA. 



MARSUPIATA. 



great group, which h divide* into thre lecUoDi : the first consisting 

 of the genus Homo ; the second of th genera 5imio, Prorimia, Pro- 

 rtkut, fanitu, Lemur; and the third of the genera Dtddpha and 

 / 



Mr. Ogilby separate* his Cheiropeds (Mammals with opposeable 

 thumbs) into the three groups, Ihmaxa, Quadrumana, and Pedimana, 

 which last are charaoterued as having opposeable thumb* on the bind 

 hands only. The Pedimana consist of the families Simiada (with 

 anthropoid teeth) and the Didtiphidir (with abnormal teeth). These 

 last consist of the genera PkoKolarclot, Pltaltmguta, Pelaurut, 

 iJultlpkyi, (.'keirmecltt, Datyurtu, and Phatcoyale. ('Nat Hilt of 

 Monkeys, Opossums, and Lemurs,' Menageries.) 



Before we proceed to notice the classification proposed by Professor 

 Owen, it will be better to give an outline of the organisation of these 



The Maittii>iaia differ considerably from each other in the osseous 

 put of their structure, as might be expected in a group whose food 

 and babita vary so much. Our limits do not permit of n detailed 

 inquiry into these differences ; but the examples given in the skeletons, 

 ftkulla, and teeth represented in this article will convey a general 

 notion of the formation of the bony parte, and the modifications to 

 which they are subject. There is however one peculiarity common 

 to all, which is even found in the true Monotremes, and presents a 

 marked discrepancy from the osseous systems of the other Mammalia 

 we allude to the Marsupial bones. These are attached to the pubis, 

 and imbedded in the muscles of the abdomen, where they afford 

 support to the niaraupium, or pouch, in the females. They exist also 

 in the males, to whom their presence seems to be necessary for the 

 purposes of reproduction. These bones and their situation are shown 

 in the skeletons of the Kangaroo and Opossum. (Owen, ' On the 

 Osteology of the Manupialia.' 'Zool. Proc.,' Oct., 1838.) 



The organ* of digestion, as might be expected, vary greatly. The 

 teeth are appropriated to the food or prey to be taken, whether it be 

 flesh, insects, fruits, herbs, or roots ; and in conformity with the same 

 law, we have a simple or a complex stomach, and a corresponding 

 structure in the viscera ; the flesh-eating tribes being entirely with- 

 out a caecum, and the others possessing that appendage in a greater or 

 less degree according to circumstances. 



But it is in the organs of generation and mode of reproduction that 

 the great and striking difference exists between the Marsupials and 

 all other known Mammals. 



Professor Owen, in his paper ' On the Generation of the "Marsupial 

 Animals, with a Description of the Impregnated Uterus of the 

 Kangaroo' ('PhiL Trans.,' 1834), observes that in all the genera of 

 this group the uterus is double, and the introductory passage is 

 separated either wholly or for a considerable extent into two lateral 

 canals. Both the digestive and generative tubes terminate within a 

 common cloacal outlet, and the term Monotremata therefore, he 

 remarks, though confined to the Edentate ifarsupiata, is so far appli- 

 cable to the whole of this aberrant division. As the females 

 approach the Oviparous Vertebrata in their separate genital tubes, so 

 also the males resemble them in the peculiar structure and connections 

 "of the reproductive organs. "Bothsexes," says Professor Owen, "in the 

 Marsupial genera manifest also their affinity to the oviparous classes 

 in possessing two superior ven;c cava>, and in the want of the inferior 

 nes enteric artery ; and the marsupial bones, so common in the skele- 

 tons of reptiles, are limited in the mammiferous class to this division, 

 in which alone, from the peculiarly brief period of uterine gestation, 

 and the consequent non-enlargement of the abdomen, their presence 

 might be expected. But these bones serve important purposes in 

 relation to the generative economy of the Manupiala. In the female 

 they assist in producing a compression of the mammary gland neces- 

 sary for the alimentation of a peculiarly feeble offspring, and they 

 defend the abdominal viscera from the pressure of the young as these 

 increase in size during their mammary or marsupial existence, and 

 still more when they return to the pouch for temporary shelter." In 

 the males, with the exception of the edentate genera, the marsupial 

 bone*, from their relation to the cremaster muscles, which wind round 

 them like pulleys, aUt in the acts of compression and retraction. 

 The minute size of the young of the American Opossum when found 

 in the marsupium, their pendulous attachment to the nipples, and 

 perhaps the mode in which the latter are developed, gave rise among 

 the earlier observers to a supposition that they were originally formed 

 from those parti; and the gemmiparous theory, which has subse- 

 quently been often revived, appears to have been prevalent (it the 

 time when Tyson first devoted his attention to the subject. 



Professor Owen, aft*r concluding, from data stated in his paper, that 

 it may be inferred that the ovum in the Kangaroo quit* the ovisao 

 in a condition corresponding to that in the ordinary Mammalia, and 

 increase* in a similar manner as it descend* in the uterus, goes on to 

 describe in minute and most interesting detail the foetus and mem- 

 branes of a Kangaroo (Macro?** major) at apparently the middle. 

 period of gestation, which in that animal continues for thirty- i^ht 

 days. The membranes consisted of an amnios, a very large vitelline 

 to, rendered highly vascular by ramifications of ompbalo-mesenteric 

 vessels, and a thin unvascular chorion. There was no placenta, nor 

 any adhesion between the exterior membrane of the 'foetus and the 



internal surface of the mother by the opposition and interlacement of 

 villi, or vessels, a* in those Mammalia, in which the placenta is re- 

 placed by a uniform villou* and vascular chorion ; the condition of 

 the fcotus was such as occurs in the viper and other ovoviviparous 

 reptiles, exoept that there was no trace of the existence of an allantoU 

 in that stage of the fcatal development. The dissection of very young 

 mammary foetuses of the Kangaroo, Phalamjiita, and Pttauria, 

 exhibited the remains of a urachus and umbilical vessels, wheuoo 

 Professor Owen concluded that at a more advanced stage of the foetal 

 an allantoia was developed. Professor Owen remarked that as the 

 jrow th of the foetus advanced, the circulating fluids became necessarily 

 more charged with decomposed particles of the organised substance ; 

 and that although the extended surface of minutely subdivided blood- 

 vessels afforded by the vitelline sac might servo both for respiration 

 and nutrition at the earliest stages, yet that at a late period, and as 

 the embryo acquired additional bulk and strength and parts, an 

 accessory apparatus for that mil appeared to be necessary. In all the 

 Rtptilia, he observed, in which the respiratory function of the foetus 

 i- not performed by the extension of vascular filaments from the 

 sides of the neck, an allantois or cseoil process, organised by umbilical 

 or hypogastrio vessels, is produced from the terminal portion of the 

 intestinal tube. In the placeutal Mammalia, where the vitelline sac 

 and vitellus are relatively smaller, the allantois makes its appearance 

 much earlier, but is developed in different proportions in the different 

 orders. It is subservient in all the placeutal Mammalia, to the im- 

 portant function of the transference of the hypogastric or umbilical 

 arteries to the exterior enveloping membrane or chorion ; and in these 

 Mammalia, Professor Owen further remarked, the umbilical vessels 

 co-extended with the allantoic ciccuin seek a more intimate contact 

 with the vascular surface of the womb, and proceed to organise the 

 chorion shooting out into villi, either extended over the whole surface, 

 as in the mare, or disposed in circumscribed tufts, as in the ruminants, 

 or limited to one place and forming a single placenta, as in the human 

 subject, and in all uuguiculate mammals. 



^ As connected with this subject Professor Owen subsequently 

 exhibited a preparation ('Magazine of Natural History,' vcl. i. N. S.) 

 to the Zoological Society of London, and took occasion to observe that 

 in the bird and reptile the umbilical vessels are limited to the allantois, 

 and do not extend beyond that membrane to the chorion ; the allan- 

 tois therefore plays a primary part in the respiration of the footus. In 

 the placeutal Mammalia, on the other band, its office as a temporary 

 respiratory organ is secondary, but it is essential as a means of 

 transference of the umbilical vessels to the choriou ; it has therefore a 

 pre-existence to the placenta, and without it the placenta could not 

 be formed ; for if it be considered that the embryo is formed within 

 the bag of the chorion, and is originally free from any connection with 

 that membrane, there must of necessity be some support for the 

 umbilical vessels during their passage to the chorion ; but no other is 

 known except the allnntois, or urinary bladder, and urachus, as its 

 remains are termed. The existence of a placenta, in Professor Owen's 

 mind, therefore infers the pre-exUteuce of an allantois, but the reverse 

 of the proposition does not therefore hold good. In birds and scaled 

 reptiles the allantois itself performs the functions of the placenta or 

 vascular choriou ; and the question to be resolved relatively to the 

 Kangaroo and other Marsupials was whether, the allantois being deve- 

 loped, it would serve as a medium for the organisation of the chorion, 

 or remain, as in the Oviparous \\i-tfbi-ala, an independent vascular 

 bag or caecum. The examination of the preparation alluded to, a 

 uterine footus of a Kangaroo placed at Professor Owen's disposal by 

 Dr. Sweatman, contributed to the solution of that question. This 

 foetus was further advanced than that described by Professer Owen in 

 ' Phil. Trans.' The digits of the hinder extremities were, in this, com- 

 pletely formed. The umbilical chord extended nearly three lines from 

 the abdominal surface of the footus ; the amnios was reflected from 

 this point to form the usual immediately investing tunic of the foetus; 

 and beyond the point of reflection, the chord divided into a very large 

 superior vascular sac, organised by the omphalo-mesenterio vessels, 

 corresponding in all respects with tho vitelline sac described and 

 figured in Professor Owen's paper in ' Phil. Trans.': but below tho 

 neck of this sac there extended a second pyriform sac, abjut one-sixth 

 the size of the vitelline sac, having numerous ramifications of the 

 uinliilic.il vessels, and constituting a true allantoU. This sac was 

 suspended freely from the end of the umbilical chord ; it had no con- 

 nection at any part of its circumference with tho chorion, and was 

 equally free from attachment to the parieties of the uterus, in which 

 the foetus was developed. 



The period of gestation (thirty-nine days) was determined in 1833, 

 in the vivarium of the Zoological Society of London, by Professor 

 Owen, whose account of thin obscure and interesting portion of the 

 natural history of the animal we here givo from bis paper in the 

 ' Phil. Trans.' : 



" ID order to inure the female to the examinations of tho pouch 

 when they should become indispensable, they were commenced six 

 clays after the copulation, which took place on the 27th of August, 

 and were repeated every morning and evening until the 5th of October, 

 when, at 7 ft.ni., the foetus was discovered in the pouoh attached to 

 the left superior nipple. On the preceding day at the same hour a 

 great quantity of tho moist brown secretion peculiar to the pouch was 



