126 



MUSEUM OF ANIMATED NATURE. 



[FnoGs. 



moist, or clammy, and pours out a fluid secretion. 

 As in snakes ami lirards, the cuticle is t'lTquently 

 shed and renewed. The lorm is vaiiable ; some- 

 times the limbs are wantini;: the skull is united to 

 the vertebial column by two condyles, or articulat- 

 ing processes, instead of bv a single moce»s, as in 

 snakes and lizards. When \\ie fore-limbs are present 

 there is (more or less developed) a sternal or breast 

 bone ; the ribs are cither rudimentary or wanting. 

 The toes are unfurnished with claws, but sometimes 

 protected by little homy sheaths. 



We cannot here overlook the curious fact, that in 

 some, as the frog, the humid and delicate skin co- 

 operates with the lungs, affording an extensive 

 surface for the aeration of the blood in the muiute 

 capillary vessels. This cutaneous respiration can 

 only take jilacc, as various experiments tend to 

 prove, while the skin is bedewed with moisture ; 

 hence the abundant secretion of fluid for the purpose 

 of preserving its necessary degree of humidity ; for, 

 as we have often observed, in hot weather, even 

 *vhen the iVog has no access to water, its skin is still 

 wet; and, as was first ascertained by Townson, a 

 peculiar sac, erroneously regarded as the bladder, 

 serves as a reservoir of pure fluid for the supply of 

 the system with the moisture necessary to the con- 

 tinuance of the vital operations.* 



We have said the amphibia commence existence 

 as aquatic beings, furnished with fringe-like tufts, 

 gills, or branchiae, for the respiration of water, and 

 that in some these branchix' remain, even when the 

 lungs are developed ; but that in most they become 

 obliterated upon the development of those organs. 

 Hence are the amphibia resolvable into two pri- 

 mary sections, namely, Caducibranchiate amphibia 

 (caducus, perishable), and Perennibranchiate amphi- 

 bia (Peiennis, persistent). 



Caducibranchiate amphibia. 



Family C^CILIAD^. 



The CsBciliadae are regarded by Cuvier as consti- 

 tuting one of the families of the serpents, '' Les ser- 

 pents nus ;" he observes however that many natu- 

 ralists place them with the amphibia, " though we 

 are ignorant whether or not they undergo any me- 

 tamorphosis." 



According to Midler, however, gill orifices have 

 been detected in a very young specimen of Caecilia j 

 in the Museum of Leyden, within which were black- : 

 coloured gills or fringes apparently fixed to gill 

 arches; the openings communicated freely with the 

 cavity of the mouth. This would appear to deter- 1 

 mine the question and justify the naturalists who 1 

 have assigned these reptiles to the present situa- | 

 tion. 



Of an elongated and snake-like form, the exam- 

 ples of this family have the skin naked, smooth, and 

 viscous, and marked with a series of annular de- 

 pressions more or less distinct. In the substance of 

 this smooth skin, thin scale-like laminae of minute 

 size are found to be embedded, in regular transverse 

 rows. The eyes are very small, and sometimes 

 either wanting or buried beneath the skin. The 

 vertebrae resemble in their form and mode of union 

 those of fishes. The head is depressed, the tongue 

 thick, rounded, and velvety, and usually presents 

 two eminences corresponding to the posterior nos- 

 trils. The lower jaw is not articulated to the skull , 

 by means of moveable pedicles as in the snakes, and 

 the tympanic bones are impacted with the other 

 cranial bones. There are palatal as well as max- 

 illary teeth ; they are strong, recurved, and simple. 

 There are, besides the true nostrils, two little pits or 

 depressions, one on each side, beneath the former, 

 and generally termed false nostrils. There is no 

 sternum, and the ribs are too short to encircle the 

 body. Fig. 2.314 exhibits the Skull of Ca:cilia in 

 two views. 



The tail is extremely short and blunt, or even 

 wanting. 



These singular reptiles are respectively natives of 

 the warmer parts of America, of India and the 

 Islands, and of Africa. MM. Dumeril and Bibron 

 enumerate eight species, assigned to four genera. 



According to M.Laprieur, the Caeciliadae are ovo- 

 viviparous, producing six or seven young at a birth : 

 their habits, however, are little understood. They 

 bury themselves in the humid earth and mud of 

 marshy places, piercing their way like worms, often 

 to the depth of several feet.- On the surface of the 

 ground they creep slowly along, and when in the wa- 

 ter swim like the eel, waving the tail and hinder part 

 of the boily from right to left. Uuvier states that 

 vegetable matters, mud, and sand, have been found 

 in the stomach of specimens examined. 



2315. — The Worm-like Cecilia 

 (^CcecSia lumbricoides). Head of; a, seen in pro- 

 file ; b, with the mouth open, showing the tongue, 



• The ikin not only pxlialfra but nbwrUs water ; according to 

 Townjwn, the frojf often fll.s«tb» a wt'i^'lit of water equal to that of its 

 own body in a very short time, and only by the skin of the abdo- 

 minal surface. It ia easv to »ee liow the moist earth will afford thii 

 essential of existence, so that the exhiilation and absorption may 

 balance each otlier. 



with its two eminences ; the internal orifices of the 

 nostrils, and the teeth. In this species no eyes are 

 to be perceived through the smooth skin that covers 

 the head; the fosset beneath each nostril is very 

 distinct. 



The general form is long and slender, the length 

 being about two feet, and the circumference of the 

 body not more than that of a common goose-quill. 

 There arc no rings or annular depressiuiis, except- 

 ing at the hinder part of the body, where they ap- , 

 pear varying in number from twelve to Hlteen. The i 

 tongue adheres by its edges completely to the lower 

 jaw, so that it is not free or capable of protrusion. | 

 The general colour is brownish or olive. The spe- 

 cies is a native of Surinam. 



2316. — Thk Hinged Cecilia ; 



(Siphonops anmtUUus). Caecilia annulata, aucf. j 



In this genus the body is cylindrical, the head 

 blunt, the teeth strong, the tongue large, and ad- 

 hering on all sides, with the surface marked with 

 vermiculil'orm furrows. • The eyes appear distinct 

 through the skin, and a little below and before each 

 is placed a fosset or false nostril. 



The ringed Caecilia is an inhabitant of Brazil, Ca- 

 yenne, and Surinam, and is remarkable for the dis- 

 tinctness of the annulations of the body generally. 

 MM. Dum6ril and Bibron state that in no specimen 

 have they been able to discover scales in the sub- 

 stance of the skin, probably from their extreme mi- 

 nuteness and the difficulty of detaching them from 

 the close coriaceous tissue. 



Referring to Fig. 2316 — a represents the Head and 

 Neck as seen in profile ; b, the open mouth, showing 

 the tongue, teeth, and internal orifices of the nos- 

 trils ; c, the terminal extremity of the body. 



2317, 2318.— Thb Two-banded C«cilia 



(Rhtnatrema bivittatum). Caecilia bivittata, auct. 



In the genus Rhinatrema the head is depressed 

 and elongated, the muzzle obtuse, the tongue vel- 

 vety. The eyes are distinct through the skin. No 

 fo.ssets either under the eyes or nostrils. 



In the two-banded Caecilia the rings are very nu- 

 merous round the body from the head to its termi- 

 nation, amounting to three hundred and forty. 

 These rings or (olds may be easily raised up, so as 

 to expose a great number of circular transparent 

 scales relieved by projecting lines, and forming a 

 sort of net. Referiing to Fig. 2317, the head and 

 under surface of the terminal extremity of the body 

 are exhibited with the species : and at Fig. 2318, a 

 is a representation of the scales. This species is be- 

 lieved to inhabit Cayenne. The general colour is 

 black, with a yellow stripe along each side. 



Family RANID^ (FROGS, &c.). 



The Anoura, or Anura, of some naturalists. 



The Ranidae, when in their adult or perfect con- 

 dition, are all destitute of a tail ; hence the terms 

 anoura, or anurous batrachians, by w hich they have 

 been denominated. In these animals the form of 

 the body is broad and short ; the limbs are four, 

 of which the hinder are mostly far longer and more 

 muscular than the anterior. The head is flat and 

 broad, the gape wide ; the cerebral cavity small, and 

 yet the brain scarcely fills it. 



Fig. 2319 represents the Skeleton of the Common 

 Frog; and Fig. 2320 that of the Cape DactyJaethia, 

 one of the Pipas or tongueless Bajrachians. 



In the frog the veitebrae are only ten in number, 

 in the pipa eight ; both are destitute of ribs : the 

 pelvic portion is greatly elongated. The sternum 

 is highly developed, and a large poition of it is 

 often cartilaginous; it receives the two clavicles, 

 and the coracoid bones, which support the scapulae. 



At Fig. 2320, a repiesents the sternum of the 

 common frog ; b that of the Dactylaethra. In the 

 latter there is a single free caudal bone, but which 

 has nothing of the vertebral form. 



In the true frogs (Phancioglosses raniformes of 

 Dnmcril) there are small teeth in the upper jaw, 

 and in most there are even palatal teeth, or rather 

 pointed processes forming a part of the bones to 

 which they are attached, as in the cases of certain 

 fislie.3. In the toads, however, the jaws are destitute 

 of teeth. 



The food of these reptiles consists of insects, 

 slugs, Sec, in the capture of which the tongue per- 

 forms a leading part. This organ, which is suft and 

 fleshy, and lubricated with a glutinous saliva, does 

 not rest upon anything analogous to the os hyoides ; 

 but is fixed to the inner part of the front of the 

 lower jaw, so that when in lepOse its base is anterior, 

 and it lies back, its apex pointing towards the 

 gullet, just the reverse of the ordinary position. 



When the animal darts it forth at the prey, it be- 

 comes considerably elongated, and turns on the pivot 

 I of its anterior fixture, being reversed in such a man- 

 ner that the surface which was undermost when the 

 tongue was lying in a state of repose in the mouth is 

 now the uppermost, the original position being re- 

 gained when it turns on its pivot back again into 



the mouth. The rapidity with which the frog or toad 



launches this organ at insects or slugs is extraortli- 

 nary, insomuch that the eye can scaicely follow the 

 movement ; never is the aim missfd ; the prey 

 touched by the tongue adheres iirmly, the viscid 

 saliva being very tenacious, and is instantaneously 

 carried to the back of the mouth, and swallowed. 



We have often presented slugs on bits of straw 

 or stick to toads, and watched with surprise the sud- 

 den disappearance of the prey, which seemed to 

 vanish from the stick as if by magic. 



It would appear that the senses of taste and smell 

 are not very acute in these animals ; their sight, 

 however, is quick and accurate ; there are lachry- 

 mal glands, and the tunica conjunctiva is pierced so 

 as to permit the tears to run into the cavity of the 

 mouth. 



With respect to the organs of hearing there is con- 

 siderable difference among these reptiles. In the 

 true frogs and the tree-frogs, the large tympanic 

 membrane is very distinct, just behind the eye, and 

 indicated by the delicacy of its structure compared 

 with the other integuments of the heaxl. In the 

 toads it is not apparent ; and in the ptpas it is pro- 

 tected by a sort of valve, as in the crocodile, in order 

 that it may not be injured by the pressure of the 

 water when the animals resoit to great depths. A 

 wide passage (the Eustachian tube) communicates 

 from the internal auditory cavity with the back of 

 the mouth (fauces), so that the tympanum is sub- 

 jected to an equal pressure under every atmospheric 

 change. It is indeed to be observed, " that the ex- 

 tent and freedom of the Eustachian passage are in 

 relation to the size and exposed condition of the 

 tympanic membrane, and perhaps also to its form, 

 which is convex externally, and therefore the more 

 liable to be affected by undue pressure from without, 

 being only supported behind at a small part of its 

 superficies." (Professor Owen.) 



The voice of the frogs generally consists, as is 

 well known, of a deep guttural croak ; though some 

 at least are capable of uttering a shrill cry of terror 

 or distress. This croaking. is produced by the air 

 being driven from the glottis into the puffed-out 

 cavity of the mouth, or into certain guttural sacculi, 

 which in the males of many species, and particu- 

 larly of the tree-frogs, are very large. This noise 

 they can produce under the water as well as on the 

 land : 



"Qaamvis sint sub aqua, sub aqua maledicere tentant ; 

 Vox quoque jam rauca est, inuataque colla tumescunt.*^ 



Ovid. Met., lilir. vi. fab. 6. 



M. Dumfiril says " la plupart (des bafrachiens) 

 coassent, mais ce coassenient est tres-different dans 

 .les diverses especes des grenouilles ; les unes 

 beuglent, aboient, grognent, ou ricannent ; d'autres 

 sifflent, piaulent, ou pipent. Certains crapauds pio- 

 duisent les sons flutes de divers instrumens a vent." 



The locomotion of these reptiles on land consists 

 of walking, running, and leaping, with different de- 

 grees of rapidity and address. Most are admirable 

 swimmers, propelling themselves through the water 

 by vigorous strokes of the hind limb aided by their 

 large webbed feet. The muscles of the thigh and 

 leg in the frog offer a great similarity to the ar- 

 rangement of the same parts in the human subject. 

 All hybernate. The frog seeks the mud at the bot- 

 tom of marshes, lakes, and ponds, congregating in 

 multitudes, which huddle together, forming a com- 

 pacted mass; the toad chooses some hole in the 

 ground, under stones, or the roots of a tree, and 

 there passes the months of winter. It is time, how- 

 ever, that we notice our pictorial specimens. 



2321, 2322.— The Water-Fkog 



(Rana Halecina, Kalm). Rana palustris, Gui5r. ; 

 Rana pipiens, Schreb ; Shad-frog, Bartram. 



This species in North America represents the 

 green or esculent frog of the European continent, 

 which it closely resembles in habits and colotn-ing. 

 In the male water-frog, however, there are no fis- 

 sures at the angles of the mouth, as in the European 

 species, for admitting the external protrusion of the 

 vocal sacculi ; and the head is of a more pointed 

 form. The orifice by which the air penetrates into 

 the vocal sacs is situated on each side immediately 

 under the Eustachian tube leading to the internal 

 ear. This species is extremely active, and when 

 pursued will take leaps clearing eight or ten feet at 

 a spring. It frequents the borders of ponds and 

 lakes. The general colour is brown, olive, olive 

 grey, olive brown, or bright yellowish green ; the 

 back is ornamented with black rounded spots, bor- 

 dered with yellow ; there is always one over each 

 orbit, and sometimes on the forehead ; a black 

 streak runs from the eye to the tip of the muzzle: 

 another forked at its posterior extremity runs above 

 the tympanum, and a third is seated on the forepart 

 of the shoulder; the jaws are marbled with black 

 and while, and a whitish yellow or bronzed stripe 

 runs along each side ol the head, and also along each 

 side of the back, where the cutaneous glands are 

 apparent. The hind limbs are maikcj with large 



