378 



CROCODILIA. 



dry specimens, it must not be forgotten that they are close together and 

 connected by strong cartilaginous or ligamentous bands.* 



The acetabulum is perforated. It has been contended that the pubis 

 is represented by a small patch of cartilage between the anterior end of 

 the ilium and the ischium, and that the pubis should be called an epipubis. 

 It is doubtful if this contention can be maintained (v. Huxley op. cit.). 

 The tarsus consists of two large proximal bones, an astragalo-navicular 

 and a calcaneum, of which the calcanemn has a strong heel-process (Fig. 

 202) ; and of two small distal bones. The fifth digit is represented by an 



imperfect metatarsal attached to the 

 fused tarsalia 4 and 5. The three pre- 

 axial digits are clawed. 



The skin is horny on the scales 

 but soft between. Each scale pos- 

 sesses a small pit in which the epi- 

 dermis is not cornified ; at the 

 bottom of these pits are a number 

 of tactile bodies in the cutis. 



There are two pairs of musk 

 secreting glands, one j)air which 

 can be everted on the throat, and 

 another pair within the lips of the 

 cloaca. 



In the brain f the cerebellum is 

 rather more developed than in 

 other reptiles and possesses a me- 

 dian vermis and two small lateral 

 lobes (Fig. 208). The eye $ is 

 provided with a small (abortive) 

 l^ecten. Lacrymal and harderian 

 glands are present. 



Alimentary canal. 

 in a single row on 

 lae, maxillae and dentaries. They 

 are lodged in sockets (thecodont) and 

 are hollow, conical structures with- 

 out roots. They are shed at intervals and replaced by new teeth 

 formed behind them and projecting as they grow into the pulp 

 cavities of their predecessors. The fourth mandibular tooth is 



* Huxley, Proc. Roy. Soc, 28, 1879, p. 395. 

 t Rabl-Ruckhard, Z. f. u\ Z., 30, 1878, p. 337. 



t D. W. Soemmerring, De ociiloruTn section-lwrizontal, Gottingen^ 

 1818, p. 59. 



Fia. 208.— Brain of Alligator, dor- 

 sal view (after Rabl Riickhard, 

 from Claus). Cb cerebellum; Mh 

 optic lobes; il/o medulla oblongata; 

 Vh cerebrum ; roman numerals are 

 cranial nerves ; IC, 2C first two 

 spinal nerves. 



The teeth are 

 the premaxil- 



