728 PHALANGER incisors are always |, the lower one very large and pro- clivous, and the canines normally -J-, of which the inferior FIG. 1. Skull of Naked-eared Cuscus (Cuscus gymnotis}. After Peters. is always minute, and in one genus generally absent. The true molars number either or f . The genera, of which not less than ten must be allowed as valid, may be arranged as follows. 4 I. Molars with curved crests, -r. (A.) Pm.2 minute or absent ; pm.i and pm.3 functional, the latter stand ing obliquely. rt. Canines separated from incisors ; tail hairy ...... 1. Phalangista. b. Canines close to incisors ; tail naked, scaly ... .2. Cuscus. (B.JPin. 2 functional ; pm.3 forming an even series with the molars. c. Without a flying membrane ; first two anterior toes opposable to rest ; tail prehensile ...... 3. Pseitdochirus. d. With a flying membrane ; toes normal ; tail bushy, non-prehensile ....................... 4. Petaurista, II. Molars with round or pointed cusps. (C.) Molars 1. Functional premolars 2 or 3 . 4 e. Lower premolar row interrupted ; upper i. 1 directed forwards ; pm.2 functionless ........ 5. Dactylopsila. /.Lower premolar row continuous; upper i. 1 directed downwards ; pm. 2 functional. a. A flying membrane .................... 6. Petaums. ^. No flying membrane .................... 7. Gymnobelideus. (D.) Molars -. g. Functional premolars - ; tail round ; no fly ing membrane .............................. 8. Dromicia. q h. Functional premolars ; tail distichous ; no fly ing membrane .............................. 9. Distoechums. i. Functional premolars ; tail distichous ; a fly ing membrane .............................. 10. Acrobata. 1. Phalangiita, Cuv. Upper incisors forming a semicircular series. Upper i. 1 scarcely larger than the others, parallel, its anterior surface flattened, point transversely truncated. Canines some way from and shorter than incisors, in front of the premaxillary - maxillary suture. a Pm. 1 small, some way separated both from canine and pm. 3 ; pm. 2 sup pressed ; pm. 3 large, obliquely placed. Molars large, quadrangular, their summits with distinct crescentic ridges. Lower incisors large ; canines very small, but persistent ; pm. 1 and pm. 2 small, or, com monly, absent ; pm. 3 large and obliquely placed ; molars like the upper ones. Dental formula. i.]4l C-T P m - rrrnj m - fffl x 2 = 34 to 38. Skull low, without frontal sinuses ; bullae scarcely inflated ; pre maxillary long ; the anterior palatine foramina almost confined to the premaxillai ; mandible with no trace of an external opening into the inferior dental canal. Feet normal; tail long and bushy, only naked for a few inches along the under-side of the tip. Range. The whole of Australia and Tasmania ; not yet found in New Guinea. This genus, by its somewhat elongated premaxillse, restriction At the point of exit from the bone, but the roots are of course situated in the maxilla.
- In this special dental formula, necessitated by the peculiar develop
ment of the teeth of the phalangers, the numbers are those of each individual tooth, the larger numbers representing fully -developed functional teeth, and the smaller the minute and functionless ones. An asterisk to one of the latter shows that the tooth is sometimes or commonly absent, though it should be remarked that the presence or absence of these minute teeth is not of any systematic importance. of the palatine foramina to the latter bones, and by the shape of its upper pin. 3 , shows a certain tendency towards the kangaroos (Macropodidse), the family to which the Phalangistidae are un doubtedly most nearly allied. The true phalangers, or opossums as they are called by the Aus tralian colonists, consist of four or five hardly separable species, of which the best known is the Vulpine Phalanger (Ph. vulpecula), so common in zoological gardens, where, however, it is seldom seen, owing to its nocturnal habits. It is of about the size and general build of a small fox, whence its name ; its colour is grey, with a yellowish white belly, white ears, and a black tail. It is a native of the greater part of the continent of Australia, but is replaced in Tasmania by the closely allied Brown Phalanger (Ph. fuliginoso). Its habits are very similar to those of the Yellow-bellied Flying- Phalanger (Petaurus auslralis) described below, except that, of course, it is unable to take the wonderful flying leaps so character istic of that animal. Like all the other phalangers, its flesh is freely eaten both by the natives and by the lower class of settlers. 2. Cuscus, Lacep. Upper incisor row angular in front. Upper i. 1 considerably longer than the others, round, pointed. Canines close against the last in cisors, longer than any of the other teeth, placed apparently on the suture. Pm. 1 well developed ; pm. 2 minute or absent ; pm. 3 large, rounded, its axis slightly oblique. Molars and all the lower teeth much as in Phalangista, but rather larger in proportion. 1^3 1 ] 2* 3 1234 Dental formula. i. r^- c. T pm. -^ ^ 3 m. " x 2 = 34 to 40. Frontal region of skull in adult animals markedly convex, owing to the presence of large frontal sinuses ; bullse not inflated ; pre maxillary bones very short ; palatine foramen entering the maxillse ; no external opening into the inferior dental canal. Feet normal ; tail long, naked and scaly for its terminal two- thirds, prehensile. Range. From Celebes to the Solomon Islands, and southwards through New Guinea to North Queensland. The cuscuses are curious sleepy-looking animals, which inhabit the various islands of the East Indian archipelago as far west as Celebes, being the only marsupials found west of New Guinea. As already noted, it was a member of this genus, the Grey Cuscus (C. orientalis), a native of Amboyna, Timor, and the neighbouring islands, which was the first Australian marsupial known to European naturalists. There are altogether about eight species known, all of about the size of a large cat ; their habits resemble those of other phalangers, except that they are said to be somewhat more carnivorous. 3. Pscudochirus, Ogilb. Upper incisor row angular. First upper incisor but little longer than the others, but nevertheless the longest tooth in the jaw. Canine small, behind suture. Pm. 1 rather small ; pm. 2 and pm. 3 larger, each with two roots, neither placed at all obliquely. Molars quadrangular, with very distinct crescentic ridges ; all the teeth from the incisors backwards forming a nearly continuous series. Lower pm. 3 only forming part of the molar series. Skull without frontal sinuses ; palatine foramina entering maxillffi, as in all the following genera except Dactylopsila ; bullae inflated ; palate generally complete ; a minute external opening into the inferior dental canal generally present in the position of the large vacuity characteristic of the Macropodidse. Ears large ; fore-feet with the first two toes together opposable to the remaining three ; tail thinly-haired, prehensile. Range. Tasmania, Australia, and New Guinea. There are about four species of this genus known, of which the commonest is Cook s Ring-tailed Phalanger (Pscudochirus caudi- volvulus], an animal discovered by Captain Cook during his first voyage, at Endeavour river, North Queensland. 4. Petaurista, Desm. Teeth almost exactly as in Pscudochirus, except that the lower canine is generally absent, as well as the minute first and second premolars. 12. 1 123 1234 Dental formula. i. ^ -- c.p; pm. -pr^Tg m - 1234 x 2 = 34 to 40. Bullffi inflated, but small ; palate generally incomplete from the level of the second molar ; a distinct external opening into the inferior dental canal. Sides of the body with a broad flying membrane stretching from the elbow to just below the knee ; ears large and hairy ; claws- long and sharp ; tail bushy, round, and non-prehensile. Habitat. New South Wales. The only species belonging to this genus is the large black Taguan Flying Phalanger (P. volans), an animal very similar to certain of the large Indian flying squirrels, and which fully agrees in its- habits with the Yellow-bellied Flying- Phalanger described below. In its affinities it seems to be, so to speak, a highly- specialized
