HERPETOLOGY OF JAPAN. 255 



The characters separating the snakes from the hzards have been 

 pointed out under the head of the latter, and it is only necessary here 

 to recall the fact that all the reptiles occurring within the boundaries 

 of this work, which have no external limbs are snakes. In southern 

 China, ranging w^est to the Himalayas, there occurs a genus of legless 

 lizards, Ophisaurus, of the family Anguidse, but the species have an 

 external ear-opening which at once distinguishes them from the 

 snakes. 



Several families of snakes are not represented in the fauna here 

 treated of. The most important of these is that of the Boidse, which 

 contains the largest snakes, the boas and the pythons," the most 

 remarkable external character of which is the rudiment of pos- 

 terior limbs in the shape of a small claw-like spur on each side near 

 the vent. They are found chiefly in the tropical regions of both the 

 Old and the New World. The Aniliidse, a small family' with one repre- 

 sentative in America and less than half a dozen species in south- 

 eastern Asia, have also rudiments of hind legs. The Leptotyplilopidx, 

 which have a very great external resemblance to the Typldopidse, but 

 with teeth only in the lower jaw, are confined to America and Africa, 

 a few species only entering Asia in the southwestern part. The JJro- 

 peltidx and Xenopeltidse are two small families, the former occupying 

 Ceylon and the mountains of southern India, the latter consisting of 

 a single species inhabiting the Malayan Archipelago and peninsula as 

 well as the adjacent portions of the mainland. Finally, the family 

 AmhlycepJialidse is a very interesting one, because of certain well- 

 marked characters in the anatomy of the skull, together with the 

 absence of the groove under the chin, so characteristic of the bulk 

 of the snakes which the Amblycephalidse resemble in most other exter- 

 nal characters. The members of this family belong mosth' to Central 

 and South America, but two genera inhabit southeastern Asia, from 

 the Himalayas to Hongkoilg south to the Malayan Archipelago and 

 the Philippines. 



The following table of the superfamilies, families, and subfamilies 

 of snakes ascertained to occur within our limits gives the essential 

 characters by which these divisions have been separated. There is 

 still considerable divergence in the opinions of authors concerning the 

 relative value of some of these divisions, but in breaking up of the 

 aglyph and opistoglyph "series" I believe that a better recognition of 

 the true relationships of their component parts can be obtained. 



° Ptjthon molitrus is sometimes included in the fauna of Formosa, on the strength 

 of 3 specimen (skin) sent by Swinhoe. Doctor Guenther (Rept. Brit. India, p. 331), 

 however, states that according to a communication from Swinhoe himself, the speci- 

 men had been imported into Formosa from China. 



