CROCODILIANS, LIZARDS, AND SNAKES. 



501 



OPHISAURUS VENTRALIS COMPRESSUS Cope. 



This subspecies is fomided on a single individual, Oat. Xo. 21359, from 

 the coast of South Carolina. Were it not for the existence of a few 

 specimens in a few respects intermediate between this form and the 

 ordinary one, there could be no doubt of its full specific distinctness. 

 Its characters are so peculiar that the least that can be accorded it is 

 the rank of subspecies. 



In the first place, the typical and only specimen has two interfrontona- 

 sal plates, one anterior to the other. This character is partly developed 

 in only one other specimen. Cat. ISTo. 10581, from Florida. Two labial 

 plates border the orbit below. These are separated by one or two rows 

 from the orbit in all the 

 si^ecimens except in the 

 type of the var. sulca- 

 tus from Dallas, Texas, 

 Avhere one labial enters 

 the orbit. A marked 

 peculiarity is the com 

 piession of the head, 

 body, and tail. The 

 body is higher than 

 wide, and the dorsal 

 surface is narrow roof- 

 shaped. The tail is 

 more prominent on the 

 middle line below tlian 

 on the dorsal line, al- 

 though the latter has 

 not the flat character of 

 other individuals. In 

 fact this compression is 

 absolutely unique in the 

 genus, the typical va- 

 riety being flat-backed 

 throughout the length. 

 Another peculiarity of 

 this specimen is the narrowness of the caudal scales, which are longer 

 than wide, conspicuously so beyond the basal region. They are as 

 wide as long, or even wider in the ordinary variety. The scales of 

 the upper surfaces are in fourteen rows, of which only twelve are visi- 

 ble above the lateral fold. They are angulate roof-shaped, and are not 

 keeled. There are only two rows of scales between the canthal row 

 and the superior labials; in the ordinary form there are three. The 

 prefrontals are broadly in mutual contact, as in a few other specimens, 

 as Cat. Ko. 10584. The auricuhir fissure is about two-thirds the length 

 of the eye fissure. 



Fig. 90. 

 OPHISAUnUS VENTRALIS COMPRESSUS COPE. 



South Carolina. 



Cat. No. 21359, U.S.N. M. 



