Zoological Society, 453 



claws, which appear as appendages at the inner side of the foot, for 

 the purpose of scratching the skin and dressing the fur." 



November 13, 1838. — Professor Owen, in the Chair. 



Professor Owen exhibited to the Meeting two skulls of the full- 

 grown Koala (Lipurus cinereus, Goldf., Phascolarctos, Bl.), and two 

 of immature specimens of the same species, and demonstrated the 



peculiarities of the cranium, and especially the condition of the dental 

 system. 



In both the adult crania the dental formula was as follows : 



Incis. j^- v canin. ^ ) , prcemol. ^- v mol. ^£| = 30 : 

 it thus corresponds numerically with the formula of the genus Hy- 

 psiprymnus, and differs only in the absence of a few minute, incon- 

 stant, and functionless teeth from the dentition of many of the Pe- 

 taurists and Phalangers. The true molares in the Koala are, how- 

 ever, relatively larger and stronger than in the Potoroos and Pha- 

 langers, yet present the same general structure ; each molar is beset 

 with four three-sided pyramids, the sharp apices of which soon be- 

 come blunted by trituration, and the outer series in the upper grinders 

 are the first to be worn down ; the posterior grinder is a little smaller 

 than the rest in the upper jaw ; the true molares of the lower jaw 

 are equal amongst themselves, but narrower than those of the 

 upper jaw. The crowns of the prcemolares, or false grinders, are 

 subtriangular, broadest behind, compressed, and terminate in a cut- 

 ting edge ; those of the upper jaw have a ridge extended along the 

 inner side of their base ; they do not exceed in anteroposterior ex- 

 tent the crowns of the true grinders. The true molares of the upper 

 jaw have four fangs ; those of the lower jaw, and the prcemolares in 

 both jaws, have two fangs. The canines are situated close to the 

 maxillo-incisive suture, distant from the prcemolares half an inch ; 

 they are very small, and do not extend beyond the alveolar margin 

 further than two lines ; they terminate in an oblique cutting edge, 

 and their simple fang is closed at its extremity. Two lines anterior 

 to the canines begin the series of incisors, of which the four posterior 

 ones are of the same size as the canines ; the pair immediately behind 

 the large anterior incisors have their crowns worn flat by the appulse 

 of the two large incisors below. The two anterior incisors, upper 

 jaw, are twice as long, and as broad and thick as the posterior ones i 

 their crown is conical, slightly curved, subcompressed, beveled off 

 obliquely to an anterior cutting edge, and having a partial coating 

 of enamel, but differing from true denies scalprarii in having the ex- 

 tremity of the fang contracted and closed. The two incisors of the 

 lower jaw are longer, straighter, and more compressed than the cor- 



