454 bulletin: museum of comparative zoology. 



Ambystomidae. 



33. Salamandrella keyserlingii Dybowsk}-. 

 Siberia: Lake Baikal, 1,288 (2). 



34. Onychodactylus japonicus (Houttuyn). 



Japan: Hondo, Hakone Lake, 2,586 (4); 2,594 (5 laruae); 2,595 (9 larvae); 

 Tokio, 1,864 {larva). 



The vomerine teeth of the adults are in two arched series behind 

 the ehoanae, the two arches extending forward to a Hne through the 

 anterior edge of the ehoanae. 



The Asiatic Ambystomidae fall into two groups whose vomerine 

 dentition is rather distinct. On the one hand, those whose tooth- 

 series extends farther back in the middle than on the sides; to this 

 group belong Hynobius, Pachypalaminus, and Salamandrella. Ilyyio- 

 hius lichenatus, however, is transitional to Onychodactylus in denti- 

 tion. 



The second group of those whose vomerine series does not extend 

 farther back in the middle than on the sides includes Onychodactylus, 

 Geomolge, Batrachyperus, Ranodon, and Ambystoma. 



This backward extension of the vomerine teeth in the middle 

 means of course a quite different shape of the vomero-palatine bone. 



In Ambystoma the teeth form a nearly straight series, not widely 

 separated in the middle. In Ranodon and Batrachyperus the series 

 are widely interrupted, and they are very short. 



In Onychodactylus and Geomolge the series form a double arch, 

 convex forward, and not widely separated in the middle. 



The tooth-row in Onychodactylus is usually described as continu- 

 ous, but it is not. There are three described forms in this group. 



The most recently named is Onychodactylus russicus Nikolsky 

 (Ann. Mus. zool. Acad. sci. St. Petersburg, 1913, 18, no. 2, p. 260). 



Fortunately a Latin diagnosis is given with the Russian description. 

 It states in brief: — like japonicus but the tail shorter than the head and 

 body. The third digit of the foot is the longest. The fifth is slightly 

 shorter than the third. The head-length enters the length from gular 

 fold to anus 3-3| times. There are fifteen costal folds. The 

 appressed feet do not meet. The total length is given as 75 mm., 

 the body as pallid above, varied with dark spots, beneath immaculate 

 white. 



The type-locality is "prope sinus Ussuriiensem Sibiriae." 



