No. 514] SHORTER ARTICLES AND DISCUSSION 617 



;ili.s|>lir!ini(| lnill.-e similar ill Ut'Ilt'l 



4. Marked resemblance to Ai 

 skulls in size, shape and delicate < 



especially to Antechinomys and Sniinthopsis in inflection of 

 angle, and proportionate size of an<rle. condyle and eoronoid. 



7. Rudimentary pouch (Thomas, after Tomes ), as in Phaseolo- 

 gale and Marmosa. 



8. Fore and hind limbs about equal. 



9. Pes non-syndactyl as in Dasyures and opossums. 



10. Foot plantigrade-resembles Phascologale in number and 

 position of pads, and short (-lawless hallux (Thomas). 

 Diprotodont Characters (Thomas, Sinclair). 



1. Condition of teeth — (a) one la rut 1 lower incisor, cutting, 

 forward projecting, (6) other incisors and canine in lower jaw 

 vestigial as in Epanorthidae, (c) anterior premolars small, show- 

 ing tendency toward condition seen in Phalangers, where they 

 are vestigial. 



2. Pattern of teeth — molars like Phalanger molars rather than 

 the Polyprotodont type. In Petauroides and Trichosurus there 

 are four cusps on incipient ridges ; in Caenolestes the ridges have 

 increased in extent to form a lophodont type. 



Conclusion 



Sinclair concluded that Caenolestes is very like the primitive 

 Phalangers, and the two families are probably related, not con- 

 vergent; that, while the fossil Caenolestidae are too specialized 

 in tooth structure to be the direct ancestors of the Phalangers. 

 yet there is probably a common ancestry. Later, he gave weight 

 to the possibility of convergence to account for the resemblance 

 in tooth structure (p. 443). This latter view would seem to be 

 more in accord with the facts known about Caenolestes, for ex- 

 cepting tooth structure, there appears to be no other important 

 character which links it with the Diprotodonts and there are 

 several, as given above, which link it with the Polyprotodonts. 



