BY W. J. McKAY. 931 



muscle is in two parts. The superior or superficial portion arises 

 mainly from the parietal, and its fibres run downwards and back- 

 wards to become inserted by a tendon on the posterior part of the 

 superior surface of the capsule of the venom gland ; at the same 

 time some of the fibres are inserted more anteriorly. The deeper 

 portion of the muscle arises in great part from the postorbital, 

 and runs downwards and backwards to form the internal fibres of 

 a band of muscle which arises from the internal aspect of the 

 capsule of the gland. The muscle turns round the commissure of 

 the lips, and runs forward to be inserted on to the anterior two- 

 fifths of the external surface of the articular moiety of the mandible, 

 immediately behind the dentary. 



The muscle is thus seen to be composed of three portions, and 

 in this respect it agrees with the description given by Duvernoy 

 (5) of Naja and Bungarus. In Pseudechis and Diemenia the 

 arrangement is very similar, there being, however, more muscular 

 fibres inserted on the gland anteriorly. In Morelia the upper 

 portion of the muscle is represented, its fibres run downwards and 

 backwards, and end in a tendinous expansion which is inserted 

 on the mandible for a short distance. The muscle is, in this latter 

 snake, and the same seems to hold good for all the ColuhridcB, in 

 relation with the large lachrymal gland, and gives fibres to it to 

 form a special compressor. D' Alton describes this muscle as 

 arising by two heads in Python hivittatus. 



In JDaboia the masseter is but slightly attached to the parietal 

 bone ; it arises chiefly from the superior surface of the capsule of 

 the gland, and runs downw^ards and backwards so as to be more 

 posterior to the gland than in the Elapidce. This seems to be the 

 typical manner of origin of the masseter in vipers. 



Posteriorly the masseter is related to the posterior temporal 

 muscle, while on reflecting it the anterior and deep temporal come 

 into view together with branches of the fifth nerve, one of which 

 supplies the muscle. The muscle acts as an elevator of the 

 mandible and compressor of the venom gland, and of the lachrymal 

 gland in colubrine snakes. 



