188 MAESTJPIALIA. 



Family PHALANGISTIDiE. 



Dentition (except in Tarsi^es) :— I- f, C. (^^i), I*ni. [f£|), M. [^J. 

 The first upper incisor is strong, curved, and cutting, the other two 

 being usually smaller ; the lower incisor is cutting and generally more 

 or less proclivous. The upper canine is small and rounded, and the 

 lower either rudimentary or absent. The premolars are very variable, 

 and may either resemble the true molars or be trenchant. The true 

 molars may be either simply quadritubercular, or their tubercles 

 may either coalesce into incomplete transverse ridges, with subcres- 

 centoid summits when unworn (Phalangista), or may be laterally 

 compressed, and with a subselenodont structure (Phascolarctos), or 

 may be simply conical (Thylacoleo). The cranium is always 

 short, and large in proportion to the body. The mandible has 

 the masseteric fossa without pit or large perforation, and its condyle 

 convex and transversely elongated, but not separated by a notch 

 from the coronoid process. The limbs are of equal length; the 

 scapula and humerus being elongated, and the latter furnished with 

 an entepicondylar foramen. . The calcaneum and astragalus approxi- 

 mate to those of the PhascolomyidcB, and differ widely from those of 

 the Macropodidce. In existing forms the manus has five subequal 

 digits, which are all furnished with claws ; while in the pes the 

 second and third digits are very slender and partly united by integu- 

 ment. 



Thylacoleo agrees so essentially with the existing Phalangistince, 

 that there seems every reason for following the lead of Krefft ' in 

 regarding it as a highly specialized member of the same family. 



Subfamily Phalangistinj<;. 



The lower incisor is markedly proclivous, a tooth generally 

 regarded as a rudimental lower canine is usually present, and the 

 true molars are larger than the premolars ; pm. 4 is preceded by a 

 milk-tooth. 



Genus PSEUDOCHIRUS, Ogilby^ 

 Dentition: — I. \, C. \, Pm. |, M. ^. The crowns of the upper 

 true molars are low and broad, and carry six cusps, which are 

 laterally compressed and have an imperfect selenodont structure; 

 the upper row of incisors is angulated ; i- 1 is only slightly larger 

 than i^2 or ^_3 ; and the auditory bulla is inflated. 



^ 'Mammals of Australia,' Introd., p. 3 (1871). — Bijprotodon and Nototherium 

 are also included. 



'' Proc. Zool. Soc. 183G, p. 26. 



