CROCODILID.E 



JT. Jfnm (OocmtifM inlermatiui at Graves), Journey's False 

 UaviaL 



IWeodi/u. Jaws oblong, depraved, tapering, rather diUted at the 

 cud. Teeth "***'l"**. lower canine* fitting into a notch in the side of 

 th upper jaw. Pest fringed ; toe* webbed to the tip. Nuchal and 



vical plates forming a disc eparatod from the dorsal one by small 



g a d 



scales. The bead of the newly hatched specimens is abort, 

 gradually elongates, and after a abort time attains the form 



DoUtT? 



proper to the species ; and, through the bones becoming more solid by 

 innrssaiug age, they only alightljr alter the relative proportions of the 

 different parts, so that the form of the head, taken with the shielding 

 of the back, affords good characters for the determination of the 



C. yeresm, the Indian Crocodile. 



C. bomltfnmt, the Large-Headed Indian Crocodile. 



C. rkombi/rr, the Aque Palin. 



C. America***, the American Crocodile. 



C. maryinalut, the Margined Crocodile. 



C niyarU, the Egyptian Crocodile. 



C. faliulnt, the Muggar, or Ooa Crocodile. 



xmoft, the Wide-Faced Crocodile. 

 C. p/oiu rtMfrw, Qraves's Crocodile. 

 C. Siamentit, the Siamese Crocodile. 



Fam. II. ALUGATORIDJE (Alligators). 

 Synopsis of the Genera. 



Canine teeth of the lower jaw fitting into a pit in the edge of 

 the upper jaw. It is a native of the New World. 



Jmeart. Jaws oblong, depressed, with a ridge across the face 

 between the eyes. Hind feet scarcely webbed. Nostrils with a car- 

 tilaginous septum. EyeUds fleshy. 



Allig-itor.--J*K* oblong, depressed, with a small longitudinal rib 

 between the orbit*. Hind feet webbed. Nostrils separated by a 

 bony septum. 



Caiman. Jaws oblong, depressed. Hind feet scarcely webbed. 

 Noetrils a cartilaginous septum. Eyelids with three bony plates. 



Jaeare. Head oblong, depressed, with a ridge across the face before 

 the eyes, rounded in front. Teeth unequal, canines of lower jaw 

 each fitting into a pit in the upper jaw. Toes scarcely webbed. 

 Nuchal and cervical plates united into one group. Eyelids fleshy, 

 only partially bouy. Nostrils only separated by a cartilage. 



J.faipa, the Broad-Headed Tacare. 



J. tcbrvpt, the Yacare. 



J. liffra, the Black Yacare. 



J. p<tnttlali, the Spotted Yacare. 



J. raUi/nau, Natterer's Yacare. 



AUiyalor. Jaws oblong, very depressed, broad, nearly parallel, 

 rounded in front. Forehead with a small longitudinal ridge between 

 the orbits. Teeth unequal, the lower canines received into a pit in 

 the edge of the upper jaw. Nuchal and cervical plates separate. 

 Feet fringed behind; toes half webbed, the outer front toe free. 

 Nostrils separated by a bony septum arising from the outer edge. 

 North America. The muzzle elongates by age. 



A. Ifitrifipentu (Gray), A. Lucita of others,,the Alligator. 



Caiman. Jaws oblong, depressed, subpyramidical, rounded, and 

 swollen at the end, without any frontal ridges or maxillary pits. 



Forehead flat and smooth. Teeth , unequal, lower canine teeth 



fitting into a pit in the inner edge of the upper jaw. Eyebrow* 

 defended with three bony plates. Toes scarcely webbed. Nuchal 

 sad cervical plate* united into one group ( ? ). Tropical America. 



C. trigonal**. The Trigonal Caiman. 



C. frnlrttroKU. The Eyebrowed Caiman. 



C. fitUctft. The Swollen-Headed Caiman. 



. regard to the differences between the above-named genera, Du- 

 meril and Ribron obserre that nothing better distinguishes the Croco- 

 ditss from the Alligators than the narrowness of the muzzle behind the 

 nostrils, a narrowness which is produced by the deep notch on each side 

 of the upper mandible serving for the passage of the fourth lower tooth. 

 The Osvials. it is true, have similar notches, which are destined for 

 the same purpose ; but at the extremity of the muzzle they have also 

 two others for the reception of the front lower teeth ; in u'eu of this 

 the front lower teeth in the Crocodiles pierce the upper mandible 

 through and through. The horizontal contour of the head of the 

 Crocodiles represents In genera] the figure of an isosceles triangle 

 more or lea. elongated, depending upon the sis* of the jaws ; but in 

 no CSM is the muni* wider than that of the Caimans, nor more slender 

 than that of the Oa vials. The Crocodiles have, like the former, their 

 jaws festooned, M it were, on their side., and their teeth unequal, but 

 to Us. number, because they have never been observed with more 

 thaa 19 on each aids above, and 10 on each side below. The cranial 

 holes an .larger than they are in the Caimans, and less wide than they 

 are in the Oavials. Their diameter is always found to be less than 

 that of the orbits. The nasal aperture is oval or subcircular. There 

 very small bony piste in the thickness of the upper eyelid. 



The same remark, as to the length of the head in proportion to its 

 width at the three principal epochs of life, applies to the Caimans as 

 well as to the Crocodiles. 



The greater part of the Saurian* of this group have the hind toes, 

 the three]external ones at least, united up to their extremity by a wide 

 natatory membrane. There are indeed some nevertheless in which it 

 in shorter, and one species, Crocodilm rhonbifer, wants the membrane 

 almost entirely, in the interval of the two inner toes. With about 

 two exceptions, all the Crocodiles have the posterior border of the 

 leg furnished with a dentilated crest formed of flattened scales. The 

 two species which are said not to present this character are Croco- 

 (tiltu jJaniruttrii and C. rhombifcr. 



a. Skull of Crncndiliu ntlgarit, won from above ; t, okull of Alligator ].<:ciut, 

 name view ; r, profile of skull of Crocodilm rulyaris. 



a, hin.l foot of Caiman ; i, hind foot of Crocodile. 



Only one species among the Crocodiles (Mecittopi Bennetlii, ( 

 phractiu) has its cervical scales similar, in regard to the extent wlii.'h 

 they occupy on the neck, to those of the Caimans ; that is to say, 

 they form a long band commencing behind the nape, and prolonging 

 themselves to the first dorsal plates. In the others, the cervical 

 armour occupies about the middle of the neck ; so that there rcumiiui 

 before and behind it a considerable space devoid of bony pieces. The 

 scales which cover the sides of the body are flat in some, carinated in 

 others, and there are some which are provided with both Borte. The 

 carimc springing from the tail-platen to form the crent which sur- 



