933 



MURID.E. 



934 



only about 11,500 had been taken up to the same period. In both 

 forests two sorts of mice had been observed one the Short-Tailed, 

 the other the Long-Tailed Field-Mouse ; but the former was by far 

 the most numerous, particularly in Dean Forest, where it was in the 

 proportion of upwards of fifty to one Long-Tailed. 



Buffon speaks of similar depredations to plantations by the species 

 under consideration ; but though he seems to have tried the same sort 

 of trap which was used in the English forests above-mentioned, he 

 does not appear to have resorted to the plan of making holes, which 

 is stated to have been successfully employed by the farmers in the 

 neighbourhood of Liege; .but though they make the holes round, and 

 not more than four inches in diameter, and a foot deep, the success 

 seems to be complete. 



This destructive Arvicole is a burrower, though it not unfrequently 

 takes up with the subterranean retreat of another animal, that of the 

 mole, for instance. The wheat-rick and the barn are not unfrequently 

 infested by them, -but their favourite situations are low and damp. 

 Dry seasons are fatal to them. The nest is formed in some bank or 

 meadow, generally of dried grass, and from five to seven young onea 

 are produced at a birth. To this species, or to the Long-Tailed Field- 

 Mouse, the latter most probably, White appears to allude in the 

 letter containing anecdotes of the maternal affections of animals, when 

 he speaks of a remarkable mixture of instinct and sagacity which 

 occurred to him one day, when his people were pulling off the lining 

 of a hot-bed, in order to add some fresh dung : " From out of the 

 side of this bed leaped an animal with great agility that made a most 

 grotesque figure ; nor was it without great difficulty that it could be 

 taken, when it proved to be a large white-bellied Field-Mouse, with 

 three or four young clinging to her teats by their mouths and feet. 

 It was amazing that the desultory and rapid motions of this dam 

 should not oblige her litter to quit their hold, especially when it 

 appeared that they were so young as to be both naked and blind." 



This mouse is a native of Europe. 



Mr. Bell is of opinion that the Arvicola riparla of Yarrell ('Zool. Proc.,' 

 1832) is no other than the A. pratentit of Baillon and the A. rufesccns 

 of Selys-Longchamps. For the other species of Arvicole see the list at 

 the end of this article. 



Octodon. Mr. Bennett observes that " In the structure of its molar 

 teeth, Octodon may be regarded as occupying an intermediate station 

 between Poephagomyt and Ctenomyi. In Octodon the molars of the 

 upper jaw differ remarkably in form from those of the lower. The 

 upper molars have on their inner side a slight fold of enamel, indicat- 

 ing a groove tending in some measure to separate on this aspect the 

 mass of the tooth into two cylinders : on their outer side a similar 

 fold penetrates more deeply, and behind it the crown of the tooth 

 does not project outwardly to so great an extent as it does in front. 

 If each molar tooth of the upper jaw be regarded as composed of two 

 partially united cylinders, slightly compressed from before backwards, 

 and somewhat oblique in their direction, the anterior of these cylinders 

 might be described as entire, and the posterior as being truncated by 

 the removal of its outer half. Of such teeth there are, in the upper 

 jaw of Octodon, on each side, four ; the hindermost being the smallest, 

 and that in which the peculiar form is least strongly marked. In 

 Ctenomyi, all the molar teeth, both of the upper and the lower jaw, 

 correspond with the structure that exists in the upper jaw of Octodon, 

 excepting that their crowns are more slender and more obliquely 

 placed, whence the external emargination becomes less sharply defined ; 

 and also excepting that the hinder molar in each jaw is so small as to 

 be almost evanescent : as is generally the case, however, the relative 

 position of the teeth is counterchanged, and the deficiency in the 

 outline of the crown of the tooth, which in the upper jaw is external, 



Skull of Octoion. 



\, Mtn from above ; 2, profile ; 3, wen from below ; 4, lower jaw teen from 

 bore. 



is, in the lower jaw, internal. In the lower jaw of Octodon the crowns 

 of the molars assume a figure very different from those of the upper, 

 dependent chiefly on the prolongation of the hinder portion of the 

 tooth to the same lateral extent as its anterior part : each of them 

 consists of two cylinders, not disjoined in the middle where the bony 

 portion of the crown is continuous, but partially separated by a fold 

 of enamel on either side producing a corresponding notch; placed 

 obliquely with respect to the jaw they resemble, in some measure, a 

 figure of 8 with its elements flattened obliquely, pressed towards each 

 other, and not connected by the transverse middle bars. With the 

 lowers molars of Octodon those of Poephagomys, as figured by F. 

 Cuvier, correspond in structure in both jaws. Octodon thus exhibits, 

 in its dissimilar molars, the types of two genera : the molars of its 

 upper jaw represent those of both jaws of Ctenomys ; those of its lower 

 jaw correspond with the molars of both jaws of Poephagomys." 



0. Cumingii, Benn. (Dendrobius degus, Meyen). In size and shape 

 generally resembling the Water-Rat, with which Mr. Bennett thinks 

 that it is nearly connected systematically. All the feet with five toes, 

 but the innermost both before and behind very short, and separated 

 by a wide interval from the rest. Upper surface and sides brownish 

 gray, intermixed with frequent indistinct and undefined spots and 

 patches of dusky-black ; colour slightly darker towards the rump, and 

 upper surface of the entire tail, together with its under surface for 

 one-third of its length from the tip, approaching closely to black ; 

 under surface of the body dusky-gray, mingled with a shade of brown, 

 lighter and nearly white beneath the base of the tail, and deeper on 

 the breast and the neck, where it becomes almost of the same general 

 hue as the upper surface. 



Octudon Cumiiiyii. Bennett. 



Mr. Cuming thus describes the habits of 0. Cumingii in its natural 

 state: ".These animals burrow in the ground, but always under 

 brushwood fences or in low thickets. They are so abundant in the 

 neighbourhood of Valparaiso that in the high-road between that place 

 and St. Jago more than a hundred may frequently be seen at one time 

 in search of food. Sometimes, but not often, they are observed on 

 the lower branches of the shrubs, and on those which form the fencep. 

 They fly at the least alarm, and in running carry their tufted tails like 

 a bent bow. A species of horned owl feeds principally on these pretty 

 little creatures." Mr. Bennett adds, that two living specimens brought 

 by Mr. Cuming from Chili, were placed by him, in 1831, in the 

 Society's Menagerie : one of them escaped, but the other was alive 

 when Mr. Bennett wrote (December, 1835), and was as active and 

 lively as it was on its first arrival. They were rather shy, and had 

 but little playfulness. They leaped readily aud without any appear- 

 ance of exertion from the floor of their cage to a narrow perch placed 

 at the height of nearly a foot, and there remained seated at their ease. 

 Their food was vegetable. 



It is found in Chili, near Valparaiso, where Captain King informed 

 Mr. Bennett that he had seen thousands of them. (' Zool. Proc./ aud 

 ' Zool. Trans.') 



The genus Octodon is referred to the family Hystricidce by Mr. 

 Waterhouse. [HYSTRICID.E.] 



Ctenomys. Mr. Waterhouse refers this genus to the tribe Octodon- 

 tina in his family Hystricidce. [HTSTBiciDA] 



C. Magellanicus may be taken as an example. In general form it 

 seems nearly to resemble Octodon Cumingii. Toes 5, the innermost, 

 both before and behind, much shorter than the others. Tail sparingly 

 haired, but comparatively shorter than in 0. Cumingii, and destitute 

 of any marked tuft of longer hairs at its extremity. Upper surface 

 and sides brownish-gray tinged with yellow, and hardly varied by 



