INTRODUCTION. XXIII 



teroglyplia are subdivided still fai'ther into the Conoeercn, the conical tailed 

 or colubriform, and the Plafi/cerca, flat-tailed or sea snakes. The Solen- 

 oglypha, are also subdivided into Abothrophcra^ pitless vipers, and Boihro- 

 pJwra, which are marked by a pit on the side of the face between the eye 

 and nostril. 



The cosmopolitan genus FJaps contains all the North American species 

 of Conocercce. There are two species in the Southern States, and a half 

 dozen or more in Mexico. Our species are not considered dangerous. 

 Among the old world species of the division are some of the most deadly 

 of the order, such as the Cobras, 'Nnja^ of Southern Asia and Northern 

 Africa, the favorites of the Indian jugglers. As in other sections, there 

 are species which feed upon other snakes. 



The Sea Snakes, Platijcerca, have the nostrils on the top of the snout, 

 and the tail compressed so as to form a paddle. Three to five feet in length 

 is the common size ; ten feet is a great length fur the largest. They are 

 numerous in parts of the Indian Ocean. As far as known, a single species 

 has been found in fresh water, Hijd rophis semper i, from Lake Taal in the 

 Philippines. Pelamys bicolor has been taken off the coasts of Southern 

 Mexico. Sea snakes are said to approach the shores only when about to 

 give birth to the young. They feed upon marine animals of ^various kinds, 

 and are sometimes taken in the nets of the fishermen, who fear them very 

 little. 



The Ahothrophera belong to the Eastern Hemisphere. Serpents of this 

 division differ from those of the next principally in the absence of the pit 

 or lachrymal fossa. With this exception, structure, habits, effects of venom, 

 etc., are similar. 



The pit vipers, Bothrophera, are the most venomoiis of the now world 

 Ophidia. A single family, Crofalidce, has heretofore included all of them. 

 As in the pitless vipers, the fangs are the only teeth upon the maxillaries. 

 The latter are short, and rotate upon the lachrymal and frontal bones in 

 such a manner as to allow the fangs .to recline against the roof of the 

 mouth, where they are covered by an elastic membrane when not in use. 

 The fangs are replaced when shed or broken by others, which grow in a 

 reclining position behind those in function. A section of one of these fangs 

 indicates that the tooth has been folded from its sides forward and closed 

 ai'ound the groove which opens a short distance above the point. Another 

 opening at the base is opposed to the extremity of the duct from the venom 



