20 



THE VENOM OF HELODEBMA. 



]mrable with the mammahan submaxillary, as is so frequently asserted in text- 

 books. The latter gland opens by its duet on the floor of the oral cavity 

 mesial to the lower jaw, whereas the ducts of the venom gland of Heloderma 

 open to the external side of the jaw and in close association with the lips. From 

 the relative position and comjjosite structure of the poison gland, I agree with 

 Professor Stewart in considering it as the hypertrophied representative of the 

 sublabial glands of other reptiles and mammals. 



Fig. 5. — \'entral view of dissected head and neck, 

 showing the more superficial blood-vessels. 

 Drawing slightly diagrammatic, approxi- 

 mately natural size. 



1 . Submental vein. 



2. Inferior labial vein. 

 ;i. Lingual artery. 



4. Anterior jugular vein. 



.'>. Hyoid cartilage. 



(i. Facial vein. 



7. Pharynx. 



s. Internal ju^lar vein. 



9. CEsophagus. 



10. Common carotid artery. 



11. Left aortic arch. 



The nerve-supply of tlie gland is furnishetl by branches from the inferior 

 dental nerve. Four or five of these branches leave the inferior dental canal 

 through a series of minute foramina perforating the outer side of the dentary 

 bone; one branch, however, passes through a slightly larger opening in the 

 articulare. The nerves enter the gland by its mesial surface, i. e., the surface 

 applied to the bone (fig. 2). 



The vascular supply of the gland is derived from the inferior dental artery, 

 branches of which pass outward through the foramina, already mentioned as 

 transmitting the nerves, and with the latter enter the gland on its mesial side 

 (fig. 6). Here they pass in along the interlobular septa, the ramifications of 



