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Show 1867.] MR. ST. GEORGE MIVART ON PLETHODON PERSIMILIS. 697 found there, yet he fully expects that such will eventually be discovered. 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. Gunther, as before said, has detected several differences between Pl. glutinosus and the species under consideration ; he gives the distinctions thus :- " Pl. glutinosus. PL persimilis. Limbs feeble. Limbs, well developed. The length of the fore limb is The length of the fore limb is considerably less than one-half of one-half the distance between the the distance between fore and fore and hind limbs. hind limbs. The length of the hind limb is The length of the hind limb one-half of the distance between is considerably more than one-fore and hind limbs. half of the distance between fore and hind limbs. The third and fourth toes are The length of the third and much shorter than the cleft of fourth hind toes equals that of the mouth. the cleft of the mouth. Trunk with thirteen lateral Trunk with twelve lateral cross cross folds. folds. Tail subcylindrical at tbe base. Tail compressed at the base. Tongue large, covering the Tongue narrow, elliptical, not whole bottom of the mouth, its covering the whole width of the hind margin being free. bottom of the mouth, without free posterior margin. The series of palatine teeth is The series of palatine teeth is distinctly interrupted in the subcontinuous. middle. " 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 undoubtedly 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. |