72 



Annals of the Carnegie Museum. 



The present genus, as well as Hylomeryx, has the para- and meta- 

 cones of M- more nearly conical than is the case in either Bunomeryx 

 or Mesomeryx. In the latter there are, however, no mesostyles, while 

 in Bunomeryx montanus they are fairly well represented. The large 

 premolars of the present genus suggest Hylomeryx, while the minute 

 deuterocone on P- and the absence of the postero-internal tubercle 

 of M- separates the genus from both Bunomeryx and Hylomeryx. 

 The present new genus is apparently the first of the Homacodontince 

 marked by the absence of this hypocone on M-. The heavy internal 

 ledge of the postero-internal angle of the crown fills out this portion 

 of the tooth so that it has an outline practically as quadrate as that of 

 M^ in Hylomeryx. I regard the present genus as being very close 

 to Hylomeryx because of the similar meta- and paracones, the absence 

 of the mesostyle, and the robust premolars. The protocone and 

 protoconule have undoubtedly united into a solid cross-ridge on M-. 

 This supposition is expressed by the specific name, while the generic 

 name serves to express the inter-relationship of this form with prac- 

 tically all the known genera of this subfamily. 



The brain-casts of No. 2915 and 2926 are of quite large size, with 

 well marked convolutions, a distinct or rather deeply constricted area 

 between the cerebrum and cerebellum. The medulla oblongata is 

 also quite large. In No. 2915 there is still adhering to the cast a 

 portion of the parietals, which display a sagittal crest of considerable 

 prominence and length. The lower jaw of the paratype. No. 2915, 

 shows the same generally robust structure, which is seen in the type. 



M EASUREMENTS. 



Type No. 2346^ 



Antero-posterior diameter of P- to M- inclusive 16.5 mm. 



" p3 6 



Transverse " " " 4 



" P^ 6 



Antero-posterior " " " 5 



"M' 5.5 " 



Transverse " " " 6 



Antero-posterior " " P3, M-^ approximately 32 



" P4 6 " 



Transverse " " " 3-5 



"Ml 4 



Antero-posterior " " " 5-5 



" M^ 5-5 " 



Transverse " " " 4 



" M^ 4 " 



Antero-posterior " " " approximately 7 



