CATALOGUE OF SHIELD KKITli.KS. 



Garied, Oiwn, Monogr. Fossil RtpHKa of tht London Olay, 

 I □ L849 (skeleton). 



Hob. [ndiao river.-. Bengalj Nepal, Malabar. 



2. TOMISTOMA. 

 Beak of the bend conical, thiik at the base, T.vih 

 The mandibular symphysis extends to the fifteenth tooth ; 

 the hinder tooth of the upper jaw ami most of those of the 

 lower j m I into interdental pits. Premaxillarv 



hardly expanded, orbital margins not raised. 



Gavialis, sp., MiiRer,Owen, Strauch. 



lomistom , Wiegm. Arch. 1846, i. p. 122. 



Vrans. ZooL Soe. I860, \i. p. L33. 

 Rhynchosuchus, Huxley, Jbum. Proc Linn. Soc. Zool. iv. 

 p. 16, 1--"''.'. 



The upper edge of the intermaxillary bone extends back 

 ir as the Becond canine tooth ; and in this character it 

 differs from the skull of the slender-nose Crocodiles, as Cro- 

 codilus Gfravesix and Medstops catajphractus. 



Dr. Falconer, when describing the skull of Crocodihis 



in Ann. & Mag. Nat. Ili-t. 1846, xviii. p. 362, 



-.••■ •oeodilus Schlegdii constitutes the passage from 



the true Crocodiles into the Gavials," and he shows how 



the skull agrees with the Crocodiles' in the position of the 



nasal bones. 



Prof. Owen, in the first 'Essay on the Reptiles of the 

 I-ondon Clay,' Crocodiles, p. 15, observes, "The Bornean 

 species, ( 'rocodihts ScJdeydii, was in fact originally described 

 Q( « species of Gavial; but the nasal bones, as in the 

 1 from Sheppey (fig. in t. 2. f. 5), extend to the hinder 

 borders of the external nostrils." This does not agree 

 with our skull, nor with the figures of 'the skull in Blain- 

 ville"s ' Osteographie.' See also Huxley, Journ. Proc. Linn. 

 S . ZooL iv. p. 18. 



1. Tomistoma Schlegelii. (Bornean Gavial.) 



Crocodilus gavialis Schlegelii, Mutter, Naturgesch. Ost-Ind. 



t. 123. f. 1-5. 

 Crocodilus Schlegelii, Blainv. Osteon. Crocod. t. 2. f . 3 t. 5 

 f. 4. 



Briihl, Slelet. Erok. t. 8. f. 6. 

 Ow) n, Fossils of the London Clay, p. 15. 

 Burm. Gavial, t. 2. f. 7 (skull). 

 Rhynchosuchus Schlegelii, Huxley, Proc. Linn. Soc. iv. p. 17 



(1859); Ann. j- Mag. A'at. Hist. 1859. 

 Medstops Journei, Gray, Cat. Tort. fyc. B. M. p. 38 (not 



synon.). 

 Tomistoma Schlegelii, G rag. Trans. Zool. Soc. 1869, vi. p. 134. 

 I lavialia Schlegelii, Strauch, Sgn. Crocod. p. 63. 



Hab. Australasia, Borneo {Midler, Brit. Mus.). 



The two figures Of the skull in Midler c\- Schlgd, t. 3. 

 f. 1 it 2, show tin 1 dill'eronco that occurs in the form of the 

 skull of the same species. 



In the British Museum there is a young specimen in 

 spirits, and an adult skull received from the Leydon Col- 

 lection, and a very tine adult skull from Borneo, obtained 

 from Mr. Mitten. 



Earn. II. CR0C0DILID.E. 



The cervical plates forming a distinct shield, separate 

 from the dorsal shield. Teeth strong, very unequal in size, 

 hinder larger. The Oth upper and the 11th lower tooth 

 larger, like canines, the large teeth of the lower fitting 

 into pits or perforations, and the canines fitting into notches 

 on the edge of the upper jaws. Nose of both sexes 

 simple. 



The uppersido of the intermaxillary is slightly expanded 

 behind, and its hinder end is divided and separated into 

 two parts by the front end of the nasal bone. 



Crocodilidae § **, Gray, Cat. Tort, $c. B. M. p. 36, 1844. 

 Crocodilidse, Huxley, Proc. Linn. Soc Zool. iv. p. 5. 

 Crocodilus, Cuvier. 



Grag, Ann. Phil. 1825, x. p. 195. 

 Champse, Merrem, Tent. 



Professor Huxley divides this family into two genera, 

 Crocodilus and Medstops. See Journ. l'roc. Linn. Soc. 

 Zool. iv. p. 6. 



The Crocodiles when they are first hatched have a very 

 short beak to the head. This is even the case with the 

 long-beaked Medstops cataphractus, which in its very 

 young state is hardly to be distinguished in the form of its 

 beak from the young of the common Crocodile, Crocodilus 

 vulgaris. As the young obtain strength the beak developes 

 itself more or less rapidly according to the species, until 

 its normal character is attained. 



The head seems to continue of nearly the same form, 

 merely increasing in size, for some time, perhaps years ; for 

 we know little of the duration of the life of the Crocodiles, 

 and they are probably long-lived animals. As they reach 

 maturity, and as old age creeps on, the skull thickens 

 considerably, and the jaws dilate and thicken on the 

 sides. 



The growth of the teeth, which are produced in succes- 

 sion and greatly enlarge in diameter, and the enlargement 

 of the jaws proceed pari passu : the latter is also influenced 

 by the development of these teeth and the larger alveoli re- 

 quired to support them. 



