197 



CKOCODILID^E. 



CROCODILID^. 



198 



as in all the other Saurians. Besides the ordinary and the f;Jae ribs, 

 there are a set which protect the abdomen without reaching up to 

 the spine, and which appear to be produced by the ossification of the 

 tendinous portions of the recti muscles. Their lungs are not sunk 

 in the abdomen like those of other reptiles, and there are fleshy fibres 

 adhering to the part of the peritoneum which covers the liver, and 

 which present the appearance of a diaphragm, which, joined to their 

 trilocular heart, where the blood which comes from the lungs is not 

 mingled with that venous portion of it which comes from the body 

 so completely as it is in the other reptiles, slightly approximates the 

 Crocodiles to the warm-blooded quadrupeds. The auditory bone 

 (caisse) and the pterygoid apophyses are fixed to the skull as in the 

 tortoises. 



The eggs of the Crocodiles are hard, and as large as those of the 

 goose ; and these reptiles are considered to be animals in which the 

 extremes of size, taking that of the newly-hatched young and that of 

 the full grown adult as the most remote points, present the widest 

 difference. The females guard their eggs, and when they are hatched 

 take care of the young during some months. (Cuvier.) 



The dentition of the Crocodiles is peculiar. The teeth are 

 numerous, large, of unequal length, conical, hollow at the base, 

 disposed in a single row, and planted in the thick- 

 ness of the edges of the superior and inferior 

 maxillary bones, in separate cavities which may 

 be considered as true alveoli. These teeth are 

 hollowed at the base in such a manner as to 

 serve for the case or sheath of the germ of the 

 tooth destined to replace it, and which is to be 

 of greater volume ; so that, in Crocodiles, the 

 number of the teeth does not vary with age ag in 

 many other animals. 



Great solidity and strength are the results of 

 this double gomphosis, and the alveoli are more- 

 over directed obliquely from front to rear. The 

 bony edges of the jaws whence these insulated 

 teeth spring, are covered by a kind of gum. 

 Another peculiarity of admirable adaptation to 

 the necessities of the animal, may be observed in 

 the interior of the mouth of the Crocodiles. 

 Their palatine vault is nearly flat, and is not 

 pierced by the extremities of the nasal fossa;, as 

 in the majority of other reptiles. The posterior 

 nasal apertures open in the pharynx behind the 

 velum palati, which is sufficiently long to over- 

 spread that portion of the roof which is in front 

 of the orifice of the glottis. They are probably 

 the only reptiles which have a true pharynx, that from the effect of the 

 is to say, a vestibule common to the posterior rising pressure of the 

 noxtrila, the mouth, the larynx, and the (esophagus, advancing tooth. 

 This conformation, joined to the muscular struc- 

 ture of the tongue, and a peculiar expansion of the body of the os 

 hyoides, produces a kind of cartilaginous disc or valve, which can 

 be raised and applied to the velum palati above, so as to protect 

 the glottis, to which it serves the office performed by the epiglottis 

 in mammifers, while it confers on the reptile a peculiar power of 

 deglutition and respiration, of the greatest consequence to its economy 

 when it is below the surface of the water and has seized its prey in 

 that situation ; or, when the muzzle alone is above the surface, in 

 carrying on respiration. 



The following is a summary of the characters of the family Crocodi- 

 lida. Body depressed, elongated, protected on the back with solid 

 and carinated scutcheons or shields; tail longer than the trunk, 

 compressed laterally, annulated, and furnished with crests above; 

 feet four, short, the toes of the posterior feet united by a natatory 

 membrane : each foot with three claws only ; head depressed, elongated 

 into a muzzle, in front of which are the nostrils approximated upon a 

 fleshy tubercle, furnished with moveable suckers (soupapes) : gape of 

 the mouth extending beyond the skull; tongue fleshy, adherent, 

 entire, not protractile ; teeth conical, simple, hollowed at the base or 

 towards the root, unequal in length, but placed in a single row ; male 

 genital organ simple, having its exit from the cloaca, which opens 

 longitudinally. (DumeVil and Bibron.) 



No living species of this family is found in Europe, nor has any 



been yet detected in Australasia. The Alligators are peculiar to 



Ameria; the species of Oroeodilui are distributed in the Old and 



New World ; thoso of fiavlalu seem to be limited to the Ganges and 



>t,her large rivers of continental India. 



Asia, besides the Gavial of the Ganges, produces at least three true 



liles, viz. Crocodiha miff aril, C.galeatui (C. Siamensit, Schneid. ; 



inenrit, Gray ?), and C. biporcatut. Siam seems to be the prin- 



if not the only locality, where the first of these has been found ; 



while the other two appear to be natives of those rivers which have 



mouths in the Indian Ocean and the Ganges. 



Africa, where neither Caimans (A lligator) nor Gavials have yet been 



is the native country of the Crocodile a Bouclier, and 



'I ilia vulgarit : it may also be the locality of G. planirottrit of 



Graven and of Gray (C. Qraraii, Bory de St. Vincent) ; and C. 



intermtditu of Graves and of Gray (O. Jowrnei, Bory de St. Vincent), 



baga , conc 



though their geogrupliical position does not seem to be determined : 

 these may perhaps come from the coast of Guinea. The only part of 

 Africa whence the Crocodile a Bouclier has been received is Sierra 

 Leone ; while Crocodiliis vidyaris seems to be spread over the whole 

 of Africa, and is also an inhabitant of Madagascar. Numbers have 

 been taken in the Nile, and one in the river Senegal. (Dumeril and 

 Bibron.) 



America is most fruitful in Crocodiles, and possesses more species 

 than Asia and Africa put together. True Crocodiles have never been 

 detected on the continent. C. acutus has been found at Martinique 

 and St. Domingo, and C. rjiombifer at Cuba. The northern part of 

 America is inhabited by one species only, Alligator Lucius, while four 

 species, viz. Alligator palpebrosus, A. sderops, A. punctulatitt, and A. 

 cynocephalus, inhabit the south. (Dume'ril and Bibron.) 



Cuvier says that the Crocodilidce inhabit fresh-water, that they 

 cannot swallow while in the water, but drown their prey and place 

 it in some nook under water, where they suffer it to putrefy before 

 they eat it. This account seems to require some modification. Sir 

 Charles Lyell, in his ' Principles of Geology,' observes that the larger 

 Gangetic species descends beyond the brackish water of the Delta into 

 the sea : and other instances are recorded of the true Crocodiles (but 

 not of the Alligators) frequenting the mouths of large rivers, and 

 even passing between different islands at considerable distances from 

 each other. [ALLIGATOR.] This should be remembered by geologists. 

 Then, as to their inability to swallow while in the water, those authors 

 who describe their collective fishing expeditions, entirely contradict 

 it. True it is, according to them, that the Alligators, after they have 

 seized the fish from below, rise to the surface and toss the fish into 

 the air to get rid of the water which they have taken in with it, 

 catching it again in its descent : but it is clear that they swallow it 

 without resorting to the land, though they go thither for the purpose 

 of devouring those land animals which they have succeeded in 

 capturing and drowning, after they have undergone some degree of 

 decomposition. 



" The laying of the eggs," says M. Ricord, " takes place in April 

 and May, and the number amounts from 20 to 25, more or less, laid 

 at many times. The female deposits them in the sand with little 

 care, and scarcely covers them. I have met with them in the lime 

 which the masons had left on the bank of the river. If I have 

 reckoned right, the young come forth on the fortieth day, when the 

 temperature is not too cold. At their birth they are 5 or 6 inches in 

 length. They are hatched alone, and as they can do without nourish- 

 ment while coming out of the egg, the female is in no haste to bring 

 it to them : she leads them towards the water and into the mud, and 

 disgorges for them half-digested food. The male takes no account of 

 them." The young preserve for some time the umbilical mark or 

 cicatrice on the abdomen, whereby the vitellus was absorbed. 



The Crocodilidie are generally considered as forming a natural 

 passage from the Saurians to the Chelonians, the last genera of which, 

 in certain points of their conformation and habits, approximate nearly 

 to the family under consideration. 



The following is a synopsis of the species from the ' Catalogue of the 

 Species in the British Museum' : 



Fam. I. CROCODILIM (Crocodiles). 



The lower canines fitting into a notch in the edge of the upper jaw. 

 The hind legs with a fringe of compressed scales behind. 



Synopsis of Genera. 

 * Teeth all uniform ; nose of the male very large, inflated. 



Clurialii. Jaws very long, slender, sub-cylindrical. Cervical and 

 ilorsal discs united together. 



** The ninth upper and eleventh lower teeth longer, like canines. 

 Nose of both sexes simple. 



Meciitopt. Jaws oblong, slender, depressed. Cervical and dorsal 

 discs united. Hind feet webbed. 



Crocodilut. Jaws oblong, depressed. Nuchal, cervical, and dorsal 

 discs separated from each other by small scales. 



Gavialis. Jaws very long, subcyliudrical, slender, rather dilated 

 and convex at the end. Teeth, canines two, quite anterior, small ; 

 lower canines shutting into a notch in the edge of the upper jaw. 

 Feet fringed ; toes webbed to the tip. The cervical plates united to 

 and forming a disc with the dorsal ones. Males with a large swelling 

 in front of the nostrils. Native of Asia. 



O. Gangetiau, the Gavial, or Nakoo. 



Mefistopt(Gray), Oavialia (Miiller). Jaws oblong, slender, depressed, 

 flat, without ridges. Teeth unequal, lower canines fitting into a notch 

 in the side of the upper jaw. Feet fringed ; toes webbed to the tip. 

 The cervical plates in three or four cross series united to the dorsal 

 shield. Males without any swelling in front of the nostrils. 



M. Henrietta, Bennett's False Gavial. 



M. cataphractus (Crocodilus catap/iraclus of Cuvier), the False 

 Qavial. 



