826 ON THE GLANDS AND *BETH OF POISONOUS SNAKES. [NoV. 19, 



Fig. 4. Platurus fasciatus : head from the right side. 



5. „ „ : Longitudinal section of the head taken through 



the poison-gland and duct. 



6. Hydrus platurus, var. altertians : left poison-gland and duct from side. 



7. „ „ " . » >> >' » >' above. 



8. Bistira cyanocincta : right maxilla from below. 



9. Enhydris hardwickii : „ ,, „ „ 



10. Hydr us platurus: „ „ „ „ 



11. Platurus fasciatus : „ „ „ below. 



12. „ „ „ „ „ side. 



13. ,, „ : longitudinal section through the base of the 

 external poison-fang, showing the enlargement of the duct {d.) 

 to form the vertical cavity {e.d.) ; the muscular mass {m.) is 

 situated directly in front of the base of the tooth {vide fig. 14, m.), 

 and the communication between this cavity and the groove of the 

 tooth is not shown. 



14. Enhydris hardwickii : transverse section through the bases of the 



poison-fangs, showing the communication between tlie enlarged 

 extremity of the duct and the groove of the more internally 

 situated tooth. 



15. Distira cyanocincta : transverse section of the poison-gland and the 



superior labial gland taken at a point about through the middle of 

 the eye, the former is gradually passing into the duct and the latter 

 is increasing in size anteriorly. The artery {a.) and vein (v.) are 

 the afferent and efferent blood-vessels of the large blood-sinuses 

 surrounding the maxillary teeth. 



16. Hydrus platimis, var. alternans: Harderian gland and eye. 



17. Distira cyanocincta: Harderian gland and eye. 



18. Platurus fasciatus : „ „ „ 



19. Enhydris hardwickii : Harderian gland (eye removed). 



20. Hydrus platurtcs : transverse section of poison-tooth. 



21. platurus fasciatus : transverse section of poison-tooth. 



22. Enhydris hardwickii : „ „ ,, „ 



a. Artery. 

 av. Alveoli of gland. 

 c.t. Connective tissue (interstitial). 

 d. Duct of poison-gland. 

 d.s.l. One of the ducts of superior labial gland. 

 e.d. Enlarged distal end of the duct of the poison-gland. 

 ep. Epithelial cells of duct. 

 ep.gl. Glandular (?) epithelial cells of duct. 

 gl.i.l. Inferior labial gland. 

 gl.s.l. Superior labial gland. 

 gr. Groove of poison-fang. 

 H.gl. Harderian gland. 



m. Muscular pad in front of the base of poison-fang. 

 mx. Maxilla. 



p. Poison-tooth (functional). 

 p.r. Poison-tooth (reserve). 

 p.c. Pulp-cavity. 

 f.gl. Poison-gland. 

 t. Transpalatine. 

 V. Vein. 



