60 



PROCEEDINGS OF THE ACADEMY OF 



[1890. 



tively shallow lower jaw ; the series is less compact ; the posterior 

 molar varies in antero-posterior diameter (see c and d, fig. 5). 



The actual structure of the superior and inferior molars, as shown 

 in the accompanying figures, is of great interest as the much worn 

 molars of the type species have always been described as quadritu- 

 bercular, and the published drawings of the Cernaysian specimens 

 have given the impression that the crowns are covered with acces- 

 sory cuspules. The eflfect of Avear upon the crown is seen in a com- 

 parison of the second upper molars shown in a and b. The latter is a 

 perfect example of the primitive tritubercular bunodont molar with 



Arctocyon. a, Astragalus and calcaneum. Abbrev. : cb, calcaneo-cuboidal 

 facet; n, astragalo-navicular facet ; (t/, astragal ar foramen ; «<;/, ac/, superior and 

 inferior astragalo-calcaneal facets. 



b, Terminal phalanx, superior, inferior and lateral views. 



the three secondary cusps, the proto- and meta-conules and hypocone 

 in their initial stages of development. This type is seen in Miodaemis 

 and Miolaphus (Platycfwerops), but is repeated in so many diflferent 

 j)hyla that, considered independently, it forms an insecure basis for 

 taxonomic deductions. The lower molars are mainly quadritubercu- 

 lar ; the anterior half of the crown, or primitive triangle, is, however, 

 prominent and in the first molar the paraconid is quite distinct. 



HYAENODICTIS, Lenioine. 



Proposed, '79, p. 5. //. Gaiidiyi, Lem. '85a, p. 204. 



G e n. c h a r. : L o w e r m o 1 a r s t r e n c h a n t with two ele- 

 vated cusps (protoconid and metaconid), and a prominent 

 heel supportingaposteriorpairof basal cusps (hy- 

 poconid and entoconid). Fourth premolar trenchant with 

 one m a i n cusp and two prominent basal cusps a n- 

 t e r i o r a n d p s t e r i r. 



