33 



of the old fang is absorbed, and the fang itself is probably 

 entirely removed at last, by falling out, or being broken off. But 

 the interesting question which now arises, and one too on which 

 there has been some obscurity, is : How, in this succession of 

 fangs, does the transference of the poison-duct from the old to 

 the new take place ? From the appearances of the specimen in 

 question, it would seem that, as the old fang is pushed aside, the 

 expanded extremity of the duct on its base leaves it, and is finally 

 transferred to the corresponding part of the new fang. There 

 would therefore be a period during which the duct communi- 

 cates with neither fang, but lies between them, as in the case in 

 question. 



If then, the appearance of a new fang took place simultane- 

 ously on both sides, the snake would be left, for a time, without 

 an effective poison-apparatus ; but, if the present case is a fair 

 example, this does not occur ; for, as above mentioned, there was 

 only one fang attached on the right side, and the new fang lying 

 behind would not probably have become anchylosed before the 

 old fang on the opposite side had been wholly replaced by the 

 new. 



The phenomena here presented, of the succession of the fang- 

 teeth, with subsequent adaptation of their vessels, appear to be 

 quite like those of the succession of ordinary teeth in the higher 

 animals. 



The poison-gland, situated in the midst of muscles behind and 

 below the eye, was of a fusiform shape, and of the size of a small 

 almond. It was invested with a thick tunic of fibrous tissue, 

 from which prolongations were given off inwardly, which em- 

 braced and supported each lobule of the gland. 



The gland is botryoidal, and carefully dissected out from all 

 its investing fibrous tissues, internal and external, it would quite 

 resemble a bunch of grapes ; each grape representing one of its 

 lobules, and the free stem the main duct leading to the fang. 

 As to the microscopic structure, each lobule is composed of the 

 branchings of the pedicle by which it is connected with the main 

 stem or duct. This ramification of canals occurs precisely as 

 in other glands ; but the tubes terminate coecally. These tubes 

 are composed of a basement membrane, covered internally with 



PROCEEDINGS B. S. N. H. — VOL. V. 3 OCTOBER, 1854. 



