PROF. OWEN ON HYPSIPRYMNODON. 577 



the legs of a pair of trousers, beyond which the hairs become abruptly very short. They 

 cease behind, leaving the heel bare, but are continued over the front and sides of the 

 tarsus, along the upper surface of the metatarsus, and along that of the phalanges of 

 toe iv as far as the claw. The dorsum of the second phalanx of the hallux and that 

 of the same part of toe v, are covered by scaly integument, like birds' toes. The 

 same integument covers the dorsum of the common sheath of the cleansing-toes 

 ii and in. 



The skull of Hypsiprymnodon (Plate LXXII. figs. 1, 2, 3) is smaller, narrower, more 

 elongated and attenuated anteriorly than in any known Potoroo — consequently departs 

 further in general form from that of the Kangaroos. The alisphenoidal bulla is rela- 

 tively smaller than in the Potoroos. The frontals are relatively narrower in proportion 

 to their length than in most Potoroos, showing rather the form of those bones in some 

 of the smaller Kangaroos and in the Dendrolagues. But the ridges continued back- 

 ward from the postorbital processes are very faintly indicated in both sexes of Hypsi- 

 prymnodon; in Denclrolagus they bound the temporal fossa? above by a well-marked 

 elevation : Hypsiprymnodon resembles Hypsiprymnus in this difference. The nasal 

 bones are larger and narrower than in any Potoroo. Their pointed ends project 4 milhms. 

 in front of the naso-premaxillary suture. A line dropped from then' tip would clear the 

 front border of the foremost incisor. The length of the nasals is 1 inch 3 lines (31 

 millims.) ; their basal breadth 4 lines (9 millims.). The fronto-nasal suture is on a 

 transverse parallel with the fore part of the orbits, not in advance thereof as in Potoroos ; 

 its position is that which obtains in Dendrolagus ; but it is transverse, not angular. The 

 lacrymal advances a little way upon the face ; it is grooved externally, and conveys the 

 duct by a canal commencing in advance of the orbit, as in other Marsupials and in Birds. 



The maxillary is pierced by two antorbital foramina, one small, 6 milhms. in advance 

 of the orbit ; the other, which is larger, and answers to the normal foramen in Kan- 

 garoos and Potoroos, is 8 millims. in advance. In Potoroos* and Kangaroos f the upper 

 premolar descends more or less in advance of the antorbital foramen ; in Hypsiprymnodon 

 the foramen is in advance of the premolar. The Potoroos differ from most Kangaroos in 

 the longer and narrower facial part of the skull anterior to the zygomata, which part 

 also tapers more anteriorly. Hypsiprymnodon carries further this difference, the cor- 

 responding part of the skull being relatively longer and more pointed than in Hypsi- 

 prymnus cuniculus e. g. The extent of the maxillary in advance of the premolar 

 exceeds that of the premaxillary ; in the Potoroos cited below reverse proportions 

 prevail. The course of the maxillo-premaxillary suture resembles that in the Potoroos : 

 the crown of the small canine projects from the lower end of the facial part of that 

 suture, as in Potoroos. The palatal plate of the maxillary has a pair of minute fora- 

 mina on the transverse line a little in advance of the premolar. The chief vacuities of 

 the bony palate are the two hinder ones, each half an inch in length, together 4 lines 

 (13 millims.) in breadth; the pair of premaxillary fissures are relatively longer and 



* Waterhouse, ' Hammalia ;' Hypsiprymnus penicillata, plate vi. fig. 3 a ; Hypsiprymnus minor, plate viii. fig. 3 5. 

 t O^en, ' Poss. Mamm. of Australia,' plate lsvi. fig. 1 (Osphranter rufus) ; plate lxxx. fig. 1 (Phascolagus eriibes- 

 eens) ; plate Lsxsiv. fig. 1 (Halmaturus ualabatus). 



