10 PHYSIOLOGY AND TOXICOLOGY 



two-tliirds of the firm fascia of the poison gland. Its fibres run backwards over 

 this body and descend between it and the middle temporal muscle. In this course 

 the fibres lie posteriorly to the suspensory ligament, and the outer ones, as they 

 fold about the articular end of the gland, lie in contact with the prolongation of 

 the external lateral articular ligament upon that body. Finally, the muscle winds 

 around the commissure of the lips, and is inserted into the lower jaw some distance 

 in front of the angle of the lips at h, Fig. 4. 



The middle and posterior temporal muscles. Figs. 4 and 5, arise chiefly from the 



Myology. Lateral view, a — u, gland ; b, anterior temporal muscle ; c, posterior temporal muscle; d, digastricua 



muscle ; e, posterior ligament of the sheath of the gland ; /, vagina dentis— the fang slightly raised. 



temporal fossa and are inserted, one behind the other, into the lower jaw. As 

 these two latter muscles descend nearly vertically, their obvious function is to 

 close the jaws. The use of the anterior temporal is in part also the closure of the 

 jaws, but its more obvious office is to press upon the poison gland, as we shall 

 presently see. 



The poison gland of the Crotalus occupies the side of the head, behind the eye, 

 and beneath the anterior temporal muscle. Fig. 5. Its posterior extremity extends 

 three or four lines beyond the commissure of the lips. Its anterior end lies below 

 and just behind the eye. Thus situated, the gland is in relation with the bony 

 surface behind the eye, with the middle temporal muscle, with nerves which emerge 

 under the suspensory ligament, and with the anterior temporal muscle above and 

 behind, where that muscle descends to its insertion. Beneath, the gland is in contact 

 with the external pterygoid muscle, with whose aponeurosis it has peculiar relations. 

 So much of the gland as lies below the anterior temporal and above the line of the 

 lip, is in relation with the skin which is here loosely connected with its fascia by 

 areolar tissue. 



The general form of the gland is that of a flattened, almond-shaped oval, the 

 posterior end being somewhat obtuse, and the anterior tapering to the duct, which 

 begins just behind and below the eyeball. 



The length of the organ, from the insertion of the articular ligament to the 

 beginning of the duct, was found to be eight-tenths of an inch, in a snake which was 

 four feet long, and weighed two pounds and two ounces. Its breadth was nearly 

 two-tenths of an inch, its thickness about one-eighth to one-tenth of an inch. 



The poison-glands of six snakes were carefully weighed, after exhausting them 

 of their contents, during the life of the snakes, and after the ducts and ligaments 

 had been removed. In the following table, the weight of the gland, and the weight 

 and length of the snake are given. 



