COMMON RINGED SNAKE. ^ 



finally into the terminal dilatation of the ureter, in which spermatozoa are found 

 at the breeding season. Each ureter opens on a dorsal papilla in the cloaca ; 

 and a groove leads from it to the apertures of the intromittent sacs. These are 

 eversible, and their inner surfaces are clothed with epidermic spines. They are 

 retracted by muscles. 



The right is often larger than the left ovary. The oviduct has a large ostium 

 with an entire margin as in all Vertebrata, save Mammalia. The two oviducts 

 fuse into a short vagina, which opens dorsally into the cloaca near its outlet. The 

 two ureters open on a dorsal papilla quite close to the same outlet. The post- 

 cloacal sacs of the female are smooth and non-eversible. 



Note on the poison glands. The white gland mentioned above in the English 

 Grass-snake becomes much enlarged in those colubriform snakes in which one or 

 more of the posterior maxillary teeth are. grooved. Such serpents were termed 

 Opisthoglypha by Bibron and Dumeril, Ophidia suspecta by Schlegel. But a serpent 

 with furrowed teeth may be found in the same family as a serpent with none but 

 solid teeth, e.g. Homalocranion with grooved and Calamaria with solid teeth in the 

 family Calamaridae. Hence the terms have been abandoned as of no classificatory 

 value. The members of certain families, however, among the colubriform snakes 

 are always opisthoglyph, e.g. Psammophidae^ Dipsadidae, and some of them appear 

 to be undoubtedly poisonous. 



The serpents belonging to the suborders, Proteroglypha and Solenoglypha, are 

 all venomous in the highest degree. In the former there is a large furrowed tooth 

 at the anterior end of the maxilla, and behind it a series of small solid teeth : in 

 the latter the maxilla is much reduced, very moveable, and provided with but a 

 single large furrowed tooth and the germs of its successors. The Proteroglypha in- 

 clude the Elapidae^ e.g. the Cobra di Capello (Naja tripudians) and the marine 

 Hydrophidae ; the Solenoglypha, the Viperidae, e. g. the English Viper (Pelias), and 

 the Crotalidae, e.g. the Rattlesnake (Crotalus horridus}. In both these sub-orders 

 the white gland (supra] reaches its maximum of development. The ligamentum 

 zygomaticum ( = an unossified jugal) which stretches internally to the gland between 

 the maxilla and the quadrate, develops a silvery fascia-like pouch enclosing the 

 gland. One of the three divisions of the temporal muscle is attached to the in- 

 ternal aspect of this pouch : and from its posterior end the masseter takes its origin 

 and passes down to the mandible. The gland is also enclosed in a tough fibrous 

 investment of its own Within this investment there is in Pelias berus loose con- 

 nective tissue with large lymphatic spaces said to be absent in Naja haje (Emery). 

 The gland tubes are united together by a fibrous coat with which the loose invest- 

 ment is continuous. The tubes are collected into bundles, and open into a single 

 duct. This duct opens above the base of the furrowed tooth, and a fold of the 

 mucous membrane surrounds both the base of the tooth and the aperture of the 

 duct. Hence the poison flows down the channel of the tooth, when the contrac- 

 tion of the muscles attached to the outermost capsule forcibly ejects it in the 

 act of closing the jaw. The poison is not only secreted in the gland tubes, but is 

 likewise stored within them. The quantity ejected is large at the first bite, but be- 

 comes less and less with successive bites. In Elaps (? all species) the poison glands 

 are much elongated, and reach far down the body. As a rule they do not extend 

 beyond the angle of the jaw. 



