CROCODTLIANS. LIZARDS, AND SNAKES. 475 



mented, fiiruishecl with short diapophyses, (chevron bones, aud neural 

 spiues to near the end of the series; the last-named standing at the 

 posterior border of the neural arch. Chevrons attached at posterior 

 eud of centrum, completely developed. Xeural spines of cervical ver- 

 tebrjB moderate; those of lumbar region low. 



Suprascapula short, wide; scapula short without proscapula; cora- 

 coid without eniargiuation; epicoracoid large. Sternum with a small 

 anterior foiitanelle and a posterior emargination and an unossifled line 

 connecting the two; a groove diverges from the fontanelle on each side 

 parallel to the coracoid border. Four sternal ribs on each side and no 

 xiphoid rod. All the ribs with short, cartilaginous, free htemapophyses. 



Ilium slender, without amjulus crista'; acetabulum not emargiuate. 

 Pubis subtransverse; pectineal process small, external. Ischium rather 

 wide, tubev an angle oidy. 



The teeth have been frecpiently described, owing to their seeming 

 adaptation to act as venom conduits to the wound they can inflict. 

 They are pleurddont and attached by a very obliqiie base rather than 

 by the side. The crown is conic and compressed acutely at the tip. 

 The anterior face is marked by a deep groove which runs external to 

 the nnddle line. It is formed by the rolling inward of the external 

 layer of the crown over the anterior face of the tooth, at the base, the 

 roll being less and less distinct upward. 



The mesenteries of Heloderma are characteristic. There is a single 

 hepatoventral, and the gastrohepatic has the usual position. The right 

 hepatic goes to the right side of the stomach, becoming a right gastro- 

 hepatic, and does not extend to the dorsal peritoneum, a character in 

 which it is unique in the Sauria. Posterior to the middle of the liver 

 they unite on the middle line as in the Teiida'. The lungs are attached 

 to the adjacent i)arts of the gastric peritoneum bj^ separate sheets, the 

 right and left gastropulmonary. Besides these there is a strong sheet 

 on each side extending from the suix'rior side of the liver near the 

 border to the body wall, forming the right and left hepatolateral. The 

 right hepatolateral does not extend along the right border of the liver 

 beyond thecephalad half. The right gastrohepatic extends along the 

 elongate right process of the liver to the genital fold of the peritoneum, 

 aud the apex of the liver sends a recurrent sheet backward, which 

 forms with the former a funnel-shaped passage. This recurrent sheet 

 might be regarded as a caudad he})atolateral. Dr. Shufeldt states' 

 that Heloderma possesses the free ventral i)eritoneum found in Varanus; 

 but this is not the case, as this structure is the usual one. 



The peritoneum forms a transverse fold at the posterior part of the 

 corpora adiposa, supporting the urinary bladder, and forming the 

 cystic mesentery. It is but loosely attached to the corpora adiposa, 

 which do not project freely from the body wall, and hence have no 

 special peritoneal pouch. They are elongate and coarsely subdivided. 



I Proc. Zool. Soc. Lond., 1890, pp. 193, 194. 



