| OCR Text |
Show 540 MR. O. THOMAS ON T H E [May 3, of its spiny fur; it is, however, a true Mus, and has no connexion with the species of Leggada, the presence of spines being in no way an essential character of that subgenus. With regard to these spines, our series of M. coxinga from Formosa shows every stage, from a specimen almost entirely spineless to one so thickly covered with spines that there are hardly any hairs. Mr. Swinhoe," in his original description, stated that the number of spines depended on age, the older specimens having the greater number; but I think season has quite as much to do with it, as we find specimens with the spines irregularly distributed in patches, as if these specimens were changing their fur with the season. This patchy arrangement, as far as one can see, could never obtain if the spines increased regularly in number according to the age of the individual. It seems probable, however, that both age and season have some connexion with the number of spines developed. By the examination of such a series as that of M. coxinga and others, we are irresistibly led to the conclusion that the presence of spines in the fur, far from being a character of generic, or subgeneric, is not even of specific importance. Dr. Jentink, of the Leyden Museum, has recently \ when describing various new species of Mus, divided the species primarily into those with spines and those without, laying great stress on this character. But I differ entirely from him as to its value ; for not only have I seen, of the following Indian species, specimens both with and without spines-M. alexandrinus var. nitidus, M. fulvescens, M. niveiventer, M. nitidulus, and M. {Leggada) buduga,-but I have also observed the same thing in two Fijian specimens of M. exulans, Peale, and in the Central-American genus Heteromys, which normally has the fur altogether spinous. On the whole, therefore, I am inclined to think that in all tropical countries, where the seasons of the year are tolerably well marked, a development of spines takes place in the summer, these falling off again in the winter. Spines are presumably a much cooler covering than hair, as all of the numerous spiny Rodents known are inhabitants of tropical or subtropical countries, and none of places with a distinctly cold climate. It is worthy of notice that it seems to be the species with the finest and softest hair which have the greatest tendency to the development of spines. Thus the coarse-haired Rats, such as Nesokia bengalensis, M. decumanus, and M. alexandrinus var. rufescens, seldom appear to produce true spines ; while, on the otherhand, the fine-haired var. nitidus, M. fulvescens, and M. coxinga are at times the most spiny of all. 9. MUS NIVEIVENTER. *M. (Eattus) niviventer, Hodgs. J. A. S. B. v. p. 234 (1836). M. niviventer, Hodgs. Ann. & Mag. Nat. Hist. xv. p. 267 (1845) ; Gray, Cat. Hodgson's Coll. (1) p. 18 (1846). Hab. The region bordering the Himalayas, from Simla to Katmandu ; Darjiling (Jerdon) ? 1 Notes from the Leyden Museum, i. p. 7 (1878). |
