17(1 



There is no greater contrast in the Diprdtodont series than that presented by the molars 

 in tlic Poi'phuya and the Paucidentata — the Kangaroos and Potoroos on the one hand, the 

 Thi/lacoleo and Plaijiaulax on the other. A trenchant tooth may exist for other pur- 

 poses than that of cutting vegetable matter, notwithstanding the stress laid by Messrs. 

 FALCONER, FLOWER, and Boyd Dawkins on the degrees of resemblance subsisting between 

 the sectorials in the Paucidentata and Po'epliaija. The differences which are pointed 

 out in the present paper outweigh the resemblances in number and importance, irre- 

 spective of the characters given by the rest of the dentition. 



Fig. 1 0. 



Macropus (Dendrolagvs) dorcocephalvs, mandible and teeth, nat. size. 



First, as to relative size. With all the additions of poephagous species made to our 

 Zoological Lists since 1840, I still find the Macropus dorcocephalus* (fig. 1G) to present 

 the nearest approach to Thijlacoleo in the relative magnitude of the trenchant premolar 

 (ib. p 4). Including with that tooth the four succeeding molars, as the " molary series," 

 the premolar constitutes nearly two fifths of that series: in Thylacoleo (fig. 14) the pre 

 molar (p 4) constitutes seven-tenths of the molary series. 



Fig. 17. Fig. 18. 



Bettongia penicUlata, mandible and teeth, 

 Hypsipriftnrius minor, mandible and teeth, __4. s j zc 



nat. size. 



In some Potoroos, Hypsiprymnus minor, II. Grayi, e. g. (fig. 17), the premolar (p *) a 

 little exceeds in fore-and-aft extent the two succeeding molars (m 1 & 2), but in most it 



teeth" (p. 38D). Dr. Falcoxer misquotes this as a " statement that in two Potoroos of Xew Guinea its antero- 

 posterior extent nearly equals that of the three succeeding molars." — X. p. 358 ; XI. p. 442. But in Dendro- 

 lagus ursinus, D. inmtus, and D. Brunii the proportion of the premolar does not exceed that of Hypsiprymnus 

 Grayi. 



* The many and small gradations which those additions have made known, in retained rudimental or func- 

 tionless canines, in hairiness of muzzle, of tail and other parts, in shape of ears, in proportion of fore aud hind 



