i8 



INTRODUCTION 



The second type is exemplified by the head of a 

 member of the genus Zamenis. 



In the descriptions, temporals 2 + 3 means two 

 superposed temporals in the first row, three in the 

 second. The internasals and the temporals, and the 

 loreal and the preocular, are sometimes absent, and 

 the prefrontal or the internasal may be single. One 

 or two large shields are in rare cases present behind 

 the parietals, and are called occipital. 



A breaking up into smaller shields takes place in 

 many snakes. In the Pythons, for instance, the 





Fig. 1 — Head of Typhlops braminus. (From "Fauna of 



British India") 



/, Frontal ; ip, interparietal ; I, labial ; n, nasal ; 0, ocular ; 

 p, parietal ; po, preocular ; prf, prefrontal ; r, rostral ; so, supra- 

 ocular. 



frontal may be divided into two by a longitudinal 

 cleft, and separated from the prefrontals by small 

 shields. In some Vipers, such as V. berus and 

 V. ursinii, in which the frontal and parietals, though 

 reduced in size, usually preserve their primitive 

 condition, the former is normally separated from the 

 supraocular by a series of small shields, and the 

 internasals and prefrontals are broken up ; in these 



