824 ME. 6. S, WEST ON THE BUCCAL GLANDS AND [NoV. 19, 



There is a mass of much-convoluted blood- sinuses all round 

 both the mandibular and maxillary teeth. These attain a most 

 astounding development in this animal, and are the most con- 

 spicuous objects present in any section (whether longitudinal or 

 transverse) containing the teeth. They were present in the other 

 genera examined but to a smaller degree, whereas in the four 

 specimens of this Snake examined they were enoi-mously developed 

 and to the same extent on both sides of the head. These sinuses 

 fill up the interstices between the teeth and also extend a con- 

 siderable distance on both sides of the jaw ; they completely 

 surround the whole of the reserve teeth. It is impossible to 

 consider that all this blood is required by the teeth, as many other 

 Snakes have comparatively much larger teeth than this, yet do not 

 possess any marked development of these sinuses. They are 

 supplied by very large blood-vessels, and their function appears 

 to be that of aquatic respiration : if so, we have to deal with 

 accessory organs of respiration, analogous to the villous processes 

 present in the mouths of soft-shelled Turtles {Amyda mutica and 

 Aspidonectes sjnrifer^), and it is worthy of remark that spongy 

 outgrowths of the mucous membrane serving a somewhat similar 

 function occur in the Electric ^e\ (Gymnotus), but that here they 

 may be utilized for aerial respiration by an animal whose respi- 

 ration is normally aquatic ^. 



EXPLANATION OF THE PLATES. 



Platb XLIV. 



Fig. 1. Dipsasfusca: head from left side. 



Kote. — Li all the figures' of the heads the skin has heen removed, the 

 connective tissue, &c., cleared away to show the glands, and the 

 folds of the mucous membrane of the mouth about the maxilla and 

 mandible removed to expose the teeth ; the glands, however, often 

 lie externally to the teeth in such a manner as to hide them. 



Fig. 2. Dipsasfttsca: left maxilla from below. 



3. Bipsas ceylonensis : left maxilla from below. 



4. Bijjsas dendrophila : „ „ „ 



5. Dipsas irregularis : Harderian gland (eye removed). 



6. Dipsasfusca: eye remo/ed, to show Harderian gland. 



7. Dipsas ceylonensis : eye removed, to show Harderian gland. 



8. ,, „ : transverse section of grooved tooth. 



9. Dipsasfusca: „ „ „ ,, 



10. Dipsas dendrophila: ,, ,, „ „ 



11. Dryophis prasinus: head from left side. 



12. „ „ : left maxilla from below. 



1 Simon H. Grage, " Pharyngeal Eespiration in the Soft-shelled Turtle," Proc. 

 Amer. Assoc. Adv. Sci. 1884, pp. 316-318. 



Simon H. & Susanna Phelps Gage, " Aquatic Eespiration in Soft-sheUed 

 Turtles," Amer. Nat. vol. xx., 1886, pp. 233-236. 



This accessory respiration also takes place in Trionyx : vide Louis Agassiz, 

 Contrib. Nat. Hist, of the U.S.A. vol. i. (Boston, 1857), pp. 283, 284. 



- Cf. Cleland, Notes on the Viscera of G-ymiwtus e/ectriciis," Memoirs and 

 Memoranda in Anatomy, vol. i. art. is. pp. 90, 91, pi. x. figs. 2, 3. 



