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Show 1867.] MR. ST. GEORGE MIVART ON PLETHODON PERSIMILIS. 695 In the heart of the Hippopotamus dissected, a very faint mark existed of the above-named division, but this would be entirely obliterated, I believe, in the adult animal. Dr. J. E. Gray places the Hippopotamus under Elephantidee, and thinks that the form is allied to the Halicoridee; but I fail to see the resemblance. The muscular band in the inferior cava described by Gratiolet is probably not found in the other pachyderms. Brain.-All the pachyderms, with the exception of the Elephant, have small brains; that of this young Hippopotamus, as before stated, weighed 10^ oz., and probably in the adult animal it would not exceed 20 oz. In an Elephant, weighing about 3 tons, I found the weight of the brain to be 12 lb. In a Tapir (T. americanus), weighing about 140 lb., the cerebral mass was 7 oz. 380 gr. In the Horse the brain weighs about 16 oz. In the Pigs it varies from 5 to 7 oz. In the Rhinoceros, as described by Professor Owen (Trans. 1862), the brain weighed 1 lb. 14£ oz. In the other members of the Hog family, and in the Babirussa, Peccaries, Hyrax, Zebra, and Quagga, judging from the skull-cavities, the brains are of small size, indicating to a great extent the slight amount of intelligence of these animals. From the above comparisons, as regards the visceral anatomy of the Hippopotamus, it will be seen that the animal differs in many important particulars from the other members of the pachyderm family. In m y next paper I hope to investigate the microscopic anatomy of the intestinal tube, and to compare the osteology of the Hippopotamus with that of the other pachyderms. 3. O n Plethodon persimilis of Gray. By ST. G E O R G E M I V A R T , F.L.S. In the Zoological Society's 'Proceedings' for 1859* Dr. Gray described and figured a species of Newt, said to be from Siam, under the name Plethodon persimilis. The author justly remarked its striking similarity in size, form, colour, &c. to Plethodon glutino-sus of North America, adding that he was at first inclined to believe that the specimens described were really American, and had been sent to Siam. From its great resemblance to the last-named species, Dr. Gray included the new one in the genus Plethodon. Dr. Giinther, in his * Reptiles of British India'f, described again the typical specimens ; but while noticing certain differences between them and Plethodon glulinosus, yet retained the species in the genus Plethodon. Having recently had occasion to examine the specimens of Urodela preserved in the British Museum, when I came to the type specimens of Pl. persimilis, while struck with their similarity to specimens of Pl. glutinosus, I was startled by their alleged habitat. * Proc. Zool. Soc. 1859, p. 230, pl. xix. f. 2. t 1864, p. 439. |
