20 



THE VENOM OF HELODERMA. 



parable with the mammalian submaxillary, as is so frequently asserted in text- 

 books. The latter gland opens by its duct 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 j aw and in close association with the lips. From 

 the relative position and composite 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. Ventral 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. 



3. Lingual artery. 



4. Anterior jugular vein. 



5. Hyoid cartilage. 



6. Facial vein. 



7. Pharynx. 



8. Internal jugular vein. 



9. (Esophagus. 



10. Common carotid artery. 



11. Left aortic arch. 



The nerve-supply of the gland is furnished 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 



