228 POISONOUS SERPENTS. 



The exceptions to this rule are, however, too numerous for its value as a 

 distinguishing character in a question of such practical moment as the 

 venomous or non-venomous properties of a serpent. In all the family 

 of marine serpents the poison-fang is only the foremost of a row of 

 fixed maxillary teeth : in the Hydrophis striatus (PI. 65, fig. 14) there 

 are four teeth, and in Hydrophis schistosa (fig. 15) five teeth, behind 

 the venom-fang, of rather smaller size than it ; the two-coloured sea- 

 snake {Pelamys hicolor) has also five maxillary teeth in addition to 

 the perforated one. The poison-fang, in this genus, is relatively 

 smaller than in the venomous serpents of the land, but presents the 

 same peculiar structure. The poison-gland presents a corres- 

 pondingly small development ; it is pyriform, and its structure, 

 according to Dr. Canter(l), is minutely cellular; it is covered 

 by the aponeurotic expansion of the articulo-maxillaris (PI. 65, 

 fig. 15, e, fj, and transmits a straight duct horizontally to the 

 basal opening of the venom-fang. It is a curious fact that the 

 smaller non- venomous teeth of the poisonous serpents all present a 

 trace of the structure of the functional venom-fang, being more or 

 less deeply grooved along the convex anterior side ;(2) and in the 

 Hydrus this groove commences by a depression analogous to the 

 oblique basal aperture of the poison-canal in the true fang. 



The colubriform poisonous serpents of the land have comparatively 

 short venom -fangs, but they are larger than those of the pelagic serpents; 

 and behind the venom-fangs there are likewise some smaller grooved 

 teeth in the maxillary bones : there are three such teeth in the Bunga- 

 rus Pama, and five in the Bungarus annulatus. In the Hamadryas or 

 great hooded poisonous tree-snake of India, the venom-fang is rela- 

 tively as large as in typical poisonous serpents, but three or four 

 smaller grooved teeth are implanted behind it on the maxillary 

 bone. 



In the most deadly venom-snakes, as the viper {Berus), the pufF- 



maxillary, and c d the palato-pterygoid series of teeth in both species. In the Naja the maxil- 

 lary series is reduced to a single fang. 



(1) Zool. Transactions, vol. ii, p. 304. 



(2) The presence of similar grooved teeth in Serpents which are not armed with venom- 

 angs has already been noticed ; such teeth are never found in the Boas and Pythons. 



