SALIVARY AND OTHEE GLANDS OF COLUBEID^. 517 



On the Histology of the Salivary, Buccal, and Harderian Glands 



of the Coluhridce, with Notes on their Tooth-successiou and 



the Eelationships of the Poison-duct. By Q. S. West, 



A.E.C.S.Lond., Scholar of St. John's Coll. Cambridge.* 



[Eead I7th February, 1898.] 



(Plates 34 & 35.) 



During the continuation in Cambridge of my work upon the 

 poison-apparatus of Snakes, commenced at the Eoyal College of 

 Science, London, upon which the Linnean Society have already 

 down me the honour of publishing a paper (Journ. Linn. Soc, 

 Zool. vol. XXV. p. 419), several matters have arisen which require 

 further consideration, more particularly as concerning the histo- 

 logical structure of the glands of the head, the nature of their 

 secretion, and the succession of the poison-teeth. In the study 

 of the more minute structure of the glands, one of the greatest 

 diflBculties met with was to procure specimens of poisonous 

 snakes sufficiently well preserved for such histological purposes, 

 and for this reason but few of the specimens examined have been 

 of real use in the preparation of this paper. 



The Gtlands. 



The Unicellular Glands. — The mucous membrane of the 

 mouth of snakes is thrown into a series of longitudinal folds ^ 

 variable in number and character, but usually conspicuously 

 present on each side of the pterygoids, maxillae, and mandibles. 

 This folding increases the area of the buccal epithelium, and as 

 the latter is of a secretory nature t, it must be regarded as an 

 arrangement accessory to deglutition. The epithelium for the 

 most part consists of unicellular mucus-secreting glands. In 

 some snakes (e. g. Dryophis mycterizans) these secretory cells 

 are more or less ovate goblet-cells ; in others (e. g. Bungarus 

 ceylonensis) they are columnar cells with somewhat acutely 

 rounded bases, and all possess a striated free border of con- 

 siderable thickness (about 6 /i). In many of the specimens which 

 had not been well preserved this border was dissociated iuto a 

 large number of vertically arranged rods, readily differentiated 



* Communicated by Prof. G. B. Howes, F.K.S., See. Linn. Soc. 

 t G-. S. West, "On the Buccal Glands and Teeth of certain Poisonous 

 Snakes," P. Z. S. 1895, p. 814 (footnote). 



LINN. JOURN. — ZOOLOGY, VOL. XXVI. 37 



