OCR Text |
Show 54 MR. J. L. BONHOTE ON [Feb. 5, Type C. Sc. leucocephalus Gray. a. 6 ad. sk. Cheimat, R. Menam ; alt. 20 m. 21st January, 1900. Type D. Sc. harmandi M.-Edw. ' b,c. S 2 ad. sk. Kampeng, R. M u Ping; alt. 110 m. 3rd February, 1900. 2 pregnant with two young. I have again been most carefully through the series of this Squirrel in the Museum, and there seems but little doubt that we have here a true instance of a polymorphic species. Without going into the outlying forms, four distinct types may be found in Siam, and are, in fact, all represented among the specimens in this collection. They have all received names at various times, but I am unable to recognize their title to specific or subspecific rank. Type A. The true Sc. finlaysoni is pure white all over, with the soles of feet aud eyes black. Type B (Sc. splendens) is of a uniform bright chestnut throughout, and, according to Mr. Lyle, is found in regions where the earth is similarly coloured. Type C (Sc. leucocephalus) is of a grizzled brown above and white below. Type D (Sc. harmandi) is similar above and chestnut below ; but amongst these last two varieties every possible mixture and combination is found. Apparently, although it must be understood that there is no such thing as an invariable rule in dealing with this species, the pure white (type A ) and type C are found on the lower levels, and as one ascends the river the tendency to red underparts increases. In the measurements of a series of skulls, they fall into two groups, separable by their size alone; the measurements of types A and B average larger than the rest, but a few skulls intermediate in size are also found to be those of individuals intermediate in colour. Furthermore,the skull of the type of Sc.finlaysoni, although quite adult, is the smallest of any in the series. There is therefore at present no alternative but to consider the various races as polymorphic forms of one species. It may perhaps be of use to future workers if I add the average measurements of part of the series of skulls and skins ; those imperfect in any of the measurements have been left out of the calculation, although measured and taken into account in my general remarks. Skins in flesh :- Head and body. Tail. Hind foot. Ear. mm. mm. mm. mm. Types A & B [5 skins] . . 219-5 221 49 22 Types C & D [16 skins] .. 201 209 44 19-5 |