FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 257 



Genus CORIPHAGUS Douglass 



Coriphagus Douglass, 1908, p. 17. 



Mixoclaenus Matthew and Granger, 1921, p. 7. 



Type. — Coriphagus montanus Douglass. 



Type of IMixoclaenus. — Mixoclaenus encinensis Matthew and 

 Granger. 



Distribution. — Middle Paleocene, Fort Union, Montana, and Torre- 

 jon, New Mexico. 



Diagnosis. — Pi 1-rooted. P3-4 subeqiial, somewhat swollen but 

 elongate, with minute anterior basal cusps and small heels basined 

 posterointernaliy. Molars relatively small, trigonids larger than talo- 

 nids and notably higher, paraconids distinct and nearly internal, 

 trigonids basined with cusps crested, poorly differentiated, and not 

 conical. M3 much reduced, with hypoconulid distinguishable but 

 not prominent. P^ with very rudimentary protocone, P* with dis- 

 tinct but small subcorneal protocone, M^~^ transverse, subquadrate, 

 outer borders angulate and emarginate, distinct hypocones postero- 

 internal to protocones and on cingula nearly enveloping the latter. 



Discussion. — Douglass based this genus and its type species on a 

 single but unusually complete lower jaw with P2-M3, found by Silber- 

 Hng in the Silberling Quarry. In 1913 and 1916 parties under Dr. 

 Granger found three '^ specimens of a similar form in the Torrejon, 

 and in 1921 Matthew and Granger described these as Mixoclaenus. 

 They then noted the resemblance of Mixoclaenus to Coriphagus 

 but cannot have realized, from Douglass' somewhat schematic figure, 

 how close it is. They decided to hold Mixoclaenus as distinct at least 

 until discovery of the upper dentition of Coriphagus. Matthew's 

 fuller description of Mixoclaenus (Pale. Alem.) was written before 

 1921 (probably in 1917) and was not corrected. It does not mention 

 the resemblance to Coriphagus. The upper dentition of Coriphagus 

 montanus is now partly known, and it has been possible to compare 

 original specimens of that species and of Mixoclaenus encinensis. The 

 conclusion is that the two species are unquestionably congeneric and 

 hence that Mixoclaenus is a synonym of Coriphagus. They compare 

 very closely in every known part, and the type species of the two 

 supposed genera differ only in size and doubtfully in sUght variations 

 of proportions. 



Douglass (1908) referred Coriphagus to the ?Insectivora, without 

 family assignment. Matthew and Granger (1921) placed '^Mixo- 

 claenus^' in the Oxyclaenidae but noted resemblances to Mioclaeninae 

 and Anisonchinae.^^ In his longer work Matthew (Pale. Mem.) has 



'8 Matthew mentions four, describing only two of them, but I can only find three in the collection. 



" Hay (1930) followed them in placing Mixoclaenus (which he wrongly ascribed to the Tiflany) in the 

 Oxycla/snidae, but he placed Coriphagus in the Plagiomenidae, a family with which it has practically nothing 

 in common. Schlosser (1923) placed Aliioclaenus (which he wrongly ascribed to the Puerco) in the Oxy- 

 claenidae and Coriphagus in the Mioclaenidae. These and other casual references are accompanied by no 

 evidence and require no discussion. 



