50 VENOMOUS SNAKES AND THE PHENOMENA OF THEIR VENOMS 



Tropidonotus tesselatus Laurenti: In the glandula labialis superior, which 

 is somewhat smaller and narrower than that of the natrix, there is present 

 the yellowish portion with large follicles. 



Coronella Icevis Merrem: This species possesses the glandula labialis 

 superior, consisting of one grayish and one yellowish portion. 



Coluber viridiflavus var. carbonarius Schreiber, or Coluber flavescens s. 

 asculapii: The ^Esculapius snake has a less-developed supralabial gland, 

 which has, however, two distinct portions, one grayish and one yellowish 

 portion. The cells forming the tubules of the yellowish portion are highly 

 granulated. The only duct is lined with high, clear, cylindrical cells greatly 

 differing from those present in the glandular tubules. The rest of the gland, 

 composed of smaller acini, has clear, epithelial cells. Leydig (1873). 



Elaphis virgatus Schlegel: In the rear part of the supralabial gland is 

 formed the yellowish portion, which is distinguished, by its firmer con- 

 sistency, from the glandula labialis superior proper. Three excretory ducts 

 are provided for the latter, but only one for the yellowish portion. The 

 structure of the yellowish part is briefly stated here. This portion (yellow) 

 is surrounded by a scantily developed connective tissue, beneath which lies 

 the lymphatic space with small, irregular, compressed meshes, from above 

 to below, which contain some lymphatic cells. The gland consists of 

 small, mostly tubular spaces, which, while rather narrow, are quite regu- 

 larly built and often present a flattened form. Each of these tubules is 

 inclosed in an extremely delicate, soft connective-tissue layer. The interior 

 of the tubule is lined with epithelia of cubic shape. The connective-tissue 

 capsule of the glandula labialis superior is weaker than that of the yellowish 

 portion. 



Ptyas korros Schlegel s. Coryphodon korros Jan: In this species the glan- 

 dula labialis superior consists of a grayish and a rear yellowish portion, but 

 the transverse sections of the two are described as similar. 



Herpetodryas carinatus Boie: No yellowish part is found in this species, 

 although the glandula labialis superior is regularly developed and surrounded 

 by a poorly developed layer of connective tissue in which a lymphatic space is 

 noticeable. In the place of the yellowish portion, which is missing even in a 

 rudimentary form, the glandula membran. nictitant. is enormously developed. 



Liophis merremii Wiedersheim: This is another example in which no 

 yellowish part is observed in the rear of the glandula labialis superior. 



Daspeltis scaber Wagler: Kathariner (1898) described in this species, 

 besides other sets of oral glands, an independent poison gland, which, accord- 

 ing to his judgment based upon the anatomical characteristics, can not be 

 considered as a specialized part of the supralabial gland. This gland is a 

 tubular, branched, and compact gland by itself and has one single central 

 duct, which opens at the corner of the upper jaw in a pocket of the mucous 

 membrane of a definite tooth. On the other hand, the glandula labialis 

 superior is composed of numerous alveolar glands which secrete their 

 product into the groove between the maxilla and the upper lip through 



