43^ SMITHSONIAN MISCELLANEOU":; COLLECTIONS [vOL. 45 



Subgenus OCHOTONA Link 



1795- OcJiotona Link, Beytrage Naturgesch., i, pt. ii, p. 74. 

 1867. Ogotoma Gray, Ann. Mag. Nat. Hist., xx, 3d ser., p. 220. 



Type. — Ochotona ochotona (Pallas). 



Geographical Distribution. — Mountains of central Asia. 



Diagnosis and Description. — Brain-case rather flattened, resembling 

 that in subgenus Pika. Skull (pi. xc, 84,062) itself rather strongly 

 arched, especially between the orbits. Interorbital region very nar- 

 row and pinched up. Incisive foramina constricted into two unequal 

 portions as they are in subgenus Pika. 



Represented by several skulls of Ochotona ladacensis. The figures 

 published by Biichner, show that O. koslozvi also belongs to this 

 subgenus. 



Subgenus CONOTHOA new 



Type. — Ocliotona roylii Ogilbv. 



Geographical Distribution. — Mountains of central Asia. 



Diagnosis and Description. — Brain-case rather rounded, whole 

 skull (pi. xc, 30,814) moderately arched from before backward, 

 rostrum relatively long, its origin less abrupt than in the other 

 subgenera. A small oval foramen, between one and two milli- 

 meters long, is found in the antero-superior part of each frontal 

 bone ; interorbital region moderately wide. The opening in the 

 maxilla is elongated triangular; just beneath this large opening there 

 is a small amount of fenestration. The incisive foramina together 

 are triangular in outline, usually not constricted into an anterior and 

 posterior portion. 



This subgenus is represented by several skulls of Ochotona roylii. 

 The figures of O. crythrotis, published by Biichner, show that it 

 undoubtedly belongs in this subgenus, although the incisive foramina 

 are constricted into two portions. 



Subgenus PIKA Lacepede 



1799. Pika Lacepede, Tableau de Divisions de Mammi feres, p. 9. 



Type. — Ochotona alpina (Cuvier). 



Geographical Distribution. — Same as for the genus. 



Diagnosis and Description. — Brain-case and whole skull (pi. xc, 

 66,678) very flat, interorbital region rather broad and flat, not 

 pinched up or arched. No foramina in the anterior part of the 

 frontals. Opening in the maxilla roundly triangular, single. In- 

 cisive foramina constricted into two unequal portions. 



Ochotona alpina illustrated by Waterhouse (pi. 11), and all the 

 American species belong to this subgenus. 



