_Dactylopsila._[59]—The genus _Dactylopsila_ is one of the forms without any trace of a flying membrane, its characters being as follows. Size medium. Body striped black and white. Ears oval, nearly naked at the ends. Fore toes of very unequal length, the fourth being enormously elongated; fourth and fifth toes of pes also markedly elongated. Claws long, moderately curved. Tail long, cylindrical, and evenly bushy, with the extremity more or less naked below. Skull narrow, but with the zygomatic arches greatly expanded; palate fully ossified. Dentition: _i_ ³⁄₃, _c_ ¹⁄₀, _p_ ³⁄₂, _m_ ⁴⁄₄. Upper incisors very large, the third being directed horizontally forwards; canine small and approximated to the third incisor, which it resembles. The fourth premolar of moderate size, with its longer axis placed obliquely. First lower incisor longer than in any other genus. Molars oblong, with four cusps. The typical _D. trivirgata_, or Striped Phalanger, inhabits the Papuan and North Australian sub-region; a second species (_D. palpator_), characterised by the still greater elongation of the fourth finger, occurring in South New Guinea. These animals are said to be of insectivorous habits, the elongated fourth finger, as in the analogous instance of the Lemuroid genus _Chiromys_, being apparently specially adapted for extracting insects and larvæ from their hiding places. _Petaurus._[60]—Size medium or small. Fur very soft and silky. A broad flying membrane extending from the outer side of the fifth digit of the manus to the ankle. Fore toes usually increasing regularly in length from the first to the fifth, but in some of the smaller species the fourth is the longest. Claws strong, sharp, and much curved. Tail long, evenly bushy to the extremity. Glands on the chest and between the ears. Skull short and wide, with the nasals expanded posteriorly, and usually two small palatal vacuities near the second molars. Auditory bullæ inflated, and variable in size. Dentition: _i_ ³⁄₂, _c_ ¹⁄₀, _p_ ³⁄₃, _m_ ⁴⁄₄. First upper incisors very large, and taller than canine. Molars with square crowns rounded at the angles, and four cusps, except in the last, which is triangular.