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Show 36 ZOOLOGY OF TilE VOYAGE OF TilE BEAGLE. minute dark hairs: the tail is long and slender, aml has small, scattered, bristly hairs, of a brown-black colour. In. Lines. In. Liues. Length from nose to root of tail of tail 7 0 6 6 Length of car from nose to car 0 7 6 of tarsus . st No. 2. Hairs along the centre of the back chiefly black, and but obscurely annulated, near the apex, with deep yellow: towards the sides of the body, and over the haunches, the hairs are more distinctly annulated, and on the sides of the body they are of a pale yellow at the apex: on the under parts the hairs are gl'ay, tipped with dirty yellowish white: the feet are of the same deep purple-brown hue as in the specimen first described. Habitat, Ascension Island, Atlantic Ocean, (July.) These two animals not only differ in the colour of the fur, one being of a grizzled brownish colour, and the other black, but there is a considerable difference in the texture of the fur. In the black specimen, the fur is vet·y soft and glossy, and the long hairs, which are abundant, are very slender. In the brown specimen, the fur is of a harsher nature, the long hairs are not so abundant, bnt longer, and less slender. On the other hand, they agree in size, dentition, the length of the head, tarsus, and ears, and differ but in a trifling degree (about three lines,) in the length of the tail. Upon comparing the Ascension Island specimens with M. Rattus, I find that, although in size they arc about one third less, yet the teeth precisely agree, not only in form, but in size. The relative proportions of the head, ears, and tarsi, also agree. Besides the general colouring of the fur, they both differ in having the hairs of the feet uniformly purple-black, those in Mus Ralltts being much paler, and even whitish, on the toes. In the character of the fur, there is much difference. The long silky hairs, which are so conspicuous in Mus Ratttts, are replaced, in the black specimen, by hairs which are scarcely to be distinguished from the ordinary fur; and in the other specimen, although rather longer and more distinct, they are short, compared with those of the black rat. " The specimen which has a black, and glossy fur, frequents the short coarse grass near the summit of the island, where the common mouse likewise occms. It is often seen running about by day, and was found in numbers, when the island was first colonized by the English, a few years since. The other, and browner coloured variety, lives in the out-houses near the sea-beach, and feeds MAMMALIA. ci · fl th ffi :n lie y on e o al of the turtles, slaughtered for . . If the settlement were destroyed I :fi l d the dally food of the mhabitants. compelled to migrate from the co~ 't eeD~:. ou~t.that this latter variety would be and, in the case just supposed ws l.d 't I xt ongmally descend from the summit? l ' ou l retreat there? d 'f co our return? It must howeve b b · an • I so, would its black d f ' r, e o served that th t 1 l' · rate rom each other by a s . ' e wo oca Itles are sepa- D pace, some miles in width f b 1 oes the summit of Ascension . 1 d . • 0 are ava and ashes. ' an Is an so Immense] t f nent, and the summit itself surrounded b a broa .· y remo e rom any. conti-possess a small quadruped pe 1. t . Y d funge of desert volcamc soiJ, . ' cu tar o Itself? Or m . b bl spectes been broug·ht by 80 1 . f · ' ore pro a y, has this new 0 I , me s up, rom some unkn r, am again tempted to ask a I d'd. own quarter of the world? common English species been' ~~an ~d I~th~ case of the. G~lapa?os rat, has the marked variety ?"-D. g ' Y Its new habitatwn, Into a strongly Mr . Dar wm· seems to have foreseen the diffi 1 . . have furnished, and although I have s en cu .t pl~blem whiCh these two rats must confess I have been exc d. t t much t1me m studying the Muridre I appears as if the brown and ebel mkg y puzzled by the , animals in question. 'It l.k . ' ac rats (M decu d 11 1 ewJse the common mouse (M 71-r ' • manus, an J.l!f. Rattus,) and ' · 1u.usculus ) * all of h · 1 fi II peregrinations and which to a ·t . d ' < w IC 1 o ow man in his h f • , ' cet am egree are depend t t ere ore be termed semi-do t' . .' en upon man, and may ject to a greater degree ofmes .tet'ammlals; like 1'eally domestic animals, are suu-aloof fi·om him. vana wn t 1an those speci·e s w1 . 1 llC l hold themselves Upon the whole then I have determined . Island specimens as one . to descnbe the two Ascension species and as variet · f th 11-r a mark of doubt since I d ' c Ies o e J.u.us Rattus, but with amm· ation havino-' in f: t b0 not posse. ss sufficient rna t en·a 1 s f'o r a n·g orous ex- ' b' ac ' ut one skm of each . t d . skeleton. I have also 1. d h vane y, an neither skull nor < app Je t e name of ins l . · t d · . or species, whichever it ma be :fi • . ~ mts, o es1gnate thts variety so marked a variety that y , f' oi,. s~tppos~ng 1t be not a distinct species, it is • a name or It IS desuable. * The great Bandicoot rat of India. (JJ:l . species above enumerated . a l I t ' I us fjtgantcw;, of llanlwiekc,) ought, perhaps, to bo added Lo the animal. ' ' 'nc 8 rong Y su spect several catalogued species will prove but v arietic~ of this |
