with Descriptions of New Forms. 163 



C. angustidens (Marsh) (Galecynus gregarius (Cope) ). 

 The species is distinguished from the latter by the l ' con- 

 stant presence of a posterior cusp in addition to the ante- 

 rior and posterior basal tubercles on P 2 , the larger M 2 , 

 larger brain case, less pronounced postorbital constric- 

 tion, and other characters" (Merriam 1906, p. 11). The 

 presence of the additional cusp on P 2 was not noted by 

 Cope nor is it shown in the figures accompanying his 

 description of the John Day specimens of C. angustidens. 

 This character appears on some of the Yale specimens of 

 the A\ mite River C. angustidens and C. pater cuius, and is 

 apparently an individual variation which can not be used 

 for specific determination. The other characters, mainly 

 dependent upon larger size, are what we should expect 

 from the John Day beds. This increase in size over the 

 "White River forms is seemingly a very constant charac- 

 ter in various genera, having representatives, in both that 

 area and the Great Plains region, of approximately the 

 same geologic age. 



This species is represented in the Marsh Collection by 

 several skulls, all from the middle John Day. The infra- 

 orbital foramen above the interval between P 3 and P 4 , size 

 and shape of the bullae, posteriorly pointed nasals, flat 

 palate, and moderate slope of basicraniai axis are all sim- 

 ilar to those in C. angustidens. Specimen No. 12733, 

 Y. P. M., from the Fossil Horse beds on Cottonwood 

 Creek, has three upper and lower premolars on the right 

 side and four on the left. It is upper John Day in age. 



A variant from the typical C. oregonensis is found in 

 skull No. 12700, Y. P. M., collected near Logan Butte, 

 Crook County, Oregon, in middle John Day beds. The 

 face and jaws are unusually long; cranium high; diame- 

 ter of postorbital constriction small; postorbital pro- 

 cesses prominent ; angle on ramus prominent ; length of 

 inferior molar-premolar series 48 mm. 



Measurements. 



(Chiefly from Cat. Xo. 12679, Y. P. M.) 



mm. 



Total skull length 103 



Diameter of brain-case, max 37 



Diameter of postorbital constriction 14 



