1867.] MR. ST. GEORGE MIVAUT ox PLETHODON PERSIMILIS. 697 



found there, yet he fully expects that such will eventually be dis- 

 covered. Nevertheless, though the appearance of some American 

 tailed amphibians was thus rendered less unlikely, yet the appearance 

 of such a genus as Plethodon, which has no representative in Japan, 

 was somewhat startling, and I therefore examined the specimens 

 with great interest and as carefully as I could. 



Dr. Giinther, as before said, has detected several differences be- 

 tween PI. ghitinosus and the species under consideration ; he gives 

 the distinctions thus : — 



"PL glutinosus. 



Limbs feeble. 



The length of the fore limb is 

 considerably less than one-half of 

 the distance between fore and 

 hind limbs. 



The length of the hind limb is 

 one-half of the distance between 

 fore and hind limbs. 



The third and fourth toes are 

 much shorter than the cleft of 

 the mouth. 



Trunk with thirteen lateral 

 cross folds. 



Tail subcylindrical at the base. 



Tongue large, covering the 

 whole bottom of the mouth, its 

 hind margin being free. 



The series of palatine teeth is 

 distinctly interrupted in the 

 middle. 



PI. persimilis. 



Limbs well developed. 



The length of the fore limb is 

 one-half the distance between the 

 fore and hind limbs. 



The length of the hind limlj 

 is considerably more than one- 

 half of the distance between fore 

 and hind limbs. 



The length of the third and 

 fourth hind toes equals that of 

 the cleft of the mouth. 



Trunk with twelve lateral cross 

 folds. 



Tail compressed at the base. 



Tongue narrow, elliptical, not 

 covering the whole width of the 

 bottom of the mouth, without 

 free posterior margin. 



The series of palatine teeth is 

 subcontiuuous. 



" In other respects both species are very similar, the Siamese form 

 being black, with small scattered whitish spots." 



In addition to these differences, I find that the Asiatic species is 

 entirely destitute of sphenoidal teeth, which, on the other hand, are 

 characteristic of the genus Plethodon. The species which un- 

 doubtedly belongs to the latter genus have, moreover, the first digit 

 of each extremity extremely short, which is not the case with P. 

 persimilis of Gray. Finally, in the Asiatic species (P. persimilis) 

 the phalanges of the manual digits (counting from the radial to the 

 ulnar side) are 2, 2, 3, 2 respectively, and the pedal digits (counting 

 from the tibial to the peroneal side) have 2, 2, 3, 4, 2 phalanges ; 

 while in Plethodon glutinosus the numbers are 1, 2, 3, 2 in the 

 manus, and 1, 2, 3, 3, 2 in the pes. 



These differences, when taken into consideration with the peculiar 

 geographical conditions, fully warrant the generic separation of the 

 species now under consideration from the Plethodon glutinosus. 



Proc. Zool. Soc— 1867, No. XLV. 



