ON Till-: EFFECTS OF THE BITE OF CERTAIN 

 OPISTI lOCLYPHOUS SNAKES.. 



By W. Horner Andrews, M.R.C.V.S. 



In the Catalogue of Snakes of the British Museum, Boulenger 

 divides the order Ophidia into rive families, of which only two, 

 the Colubridae and Viperidae, are of special interest to the patho- 

 logist. 



The members of the family Colubridae are arranged, accord- 

 ing to certain notable differences in their dentition, in three 

 divisions, viz., the aglypha, opisthoglypha and proteroglypha. 



In the aglyphous Colubridae the upper jaw bears a consider- 

 able number of teeth arranged in two series, maxillary and pala- 

 tine ; the various genera show some variation in the number and 

 disposition of these teeth, but the latter are all solid. 



In the proteroglyphous Colubridae the palatine teeth are more 

 or less similar to those of the aglypha, although generally fewer 

 in number; the maxillary teeth, on the other hand, show a striking 

 difference. 



The series of more or less small maxillary teeth shown in the 

 aglypha is here represented, on each side, by a single large tooth 

 or fang, situated towards the anterior extremity of the maxilla, 

 and, immediately behind this fang, a number of accessory or 

 replacing fangs in different stakes of development. 



The largest fang is more or less deeply grooved, and the base 

 of this groove is in communication with a duct leading from a 

 highly specialised poison-gland. 



The accessory fangs have a similar structure, but are gener- 

 ally more or less rudimentary, and covered by the membranous 

 sheath of the principal fang; occasionally one or two of these 

 teeth may approach the size of the principal fang, and penetrate 

 into any object bitten by the snake. 



The opisthoglypha are, morphologically, intermediate 

 between the two divisions described. In them the maxillary teeth 

 may be reduced in number, but there are always some solid teeth, 

 similar to those found in the aglypha. 



Towards the posterior extremity of the maxilla, however, are 

 a small number of somewhat larger -teeth possessing a distinct 

 groove. This groove does not communicate with any large and 

 highly specialised duct and poison gland, as in the proteroglyphous 

 snakes, but a glandular structure is situated in close proximity to 

 the base of these grooved teeth. 



Finally, the family Viperidse, which presents some striking 

 modifications in the maxillae and adjacent bones, is characterised 

 by the possession of one very large maxillary fang, pierced by a 

 more or less completely closed channel which communicates with 

 a duct leading from a well-developed poison gland ; there are also 

 accessorv fangs. 



With regard to the pathological effects produced by the 

 bites of snakes, many ages have passed since primitive man 

 learned from experience to recognise certain well-differentiated 

 kinds of snakes as hig[hlv venomous. 



