The Myrmecobians are insectivorous,t and shelter themselves in the hollows of trees, fre quenting most, it is said, those situations where the Port-Jackson willow abounds. In the structure and proportions of its hinder feet, ,111yrntecobius resembles the Dasyurine family ; and in the slightly developed canines, the smooth external surface of the skull, the breadth between the zygomata, and the absence of the interparietal ridges, as well as in its 5-5 Incisors 4-4 —; molars — = 48.
3--3 This dental formula characterizes a number of Marsupials commonly known in Australia by the name of Bandicoots; the hind legs are longer and stronger than the fore, and exhibit in a well-marked manner the feeble and slender conditions of the second and third digits counting from the inside, and the sudden in crease in length and strength of the fourth and fifth, or two outer toes, which are chiefly sub servient to locomotion. In consequence of the inequality of length in their extremities the mode of progression in the Bandicoots is by bounds, the hind feet being moved toge ther, and alternately with the fore feet, as in the hare and rabbit, and the crupper is raised higher than the fore-quarter. The teeth which offer the greatest range of variation in the present genus are the external or posterior incisors and the canines : the molars, also, which originally are quinque-cuspidate, have their points worn away, and present a smooth and oblique grinding surface in some species sooner than in others.
The Bandicoots which approach nearest to the Myrmecobius in the condition of the in cisive and canine teeth, are the Perameles abe sula and P. Gannii. There is a slight interval between the first and second incisor, and the outer or fifth incisor of the upper jaw is sepa rated from the rest by an interspace equal to twice its own breadth, and moreover presents the triangular pointed canine-like crown which characterizes all the incisors of Illyrtnecobius; but the four anterior incisors are placed close together and have compressed, quadrate, true incisive crowns. From these incisors the canine is very remote, the interspace being equally divided by the fifth pointed incisor, which the canine very slightly exceeds in size. In Pcram. nasuta the incisor presents the same general condition, but the canines are relatively larger, In Per. Gunnii, the outer incisor is closer to the others, which it also more nearly resembles in form than in the preceding species; but in Pcr. Lagutis, it is not separated from the rest
by a wider interval than that which intervenes between the first and second incisor. In both the preceding Bandicoots the canines are long and well developed, but the true molars have the grinding surface worn down flat in the full grown specimens which I have, had the tunity of examining.
The marsupial pouch in the Bandicoots, at least in the full-grown females of Per. nasuta, Per. obesula, and Per. Lagotis, has its orifice directed downwards or towards the cloaca, con trariwise to its ordinary disposition in the Marsupials : this direction of the pouch evi dently relates to the procumbent position of the trunk when supported on the short fore and long hind legs. In the stomach and in testines of a Perameles obesula I found only the remains of insects ; and in the examination of the alimentary canal of a Per. nasuta, Dr. Grant obtained the same results. Nevertheless the Peranieles Legotis, lately living at the Zoo logical Gardens, refused meat and meal-worms, and subsisted on vegetable food exclusively.
Genus CH1EROPUS.
The singular animal on which Mr. Ogilby has founded this genus, is briefly noticed and figured in Major Mitchell's Australia, (Vol. ii. pl. 38, p. 131,) and the individual described is preserved in the Colonial Mnseum, at Syd ney, N. S. Wales, (No. 35 of Mr. Geo. Ben nett's Catalogue.) It would appear that the two outer toes of the fore foot, which are always very small in the true Bandicoots, are entirely deficient in the Cheeropus unless some rudiments should exist beneath the skin ; at all events only two toes are apparent externally; but they are so developed and armed as to be serviceable for burrowing or progression. The inner toe is wanting on the hind-foot. Dental formula : Incisors, 4-4 ; canines, - prx 3-3 1-1molars, 3-3 ; molars, 4-4 = 46.
3-3 • 4-4 All the teeth are of small size ; the canines resemble the spurious molars in size and shape, and these are separated by intervals, as in .Myr mecobius. The marsupium opens downwards in the Charopus as in the true Bandicoots. The species described has no tail. The genus would seem by its dentition to rank between Myrmecobius and Perameles. Its digital cha racters are anomalous and unique among the Marsupialia, but are evidently a degeneration from the Saltatorial or Bandicoot type.