PLATE CXI 



Type Skull of Allops walcotti 



Plate prepared under the direction of Professor Marsh. One-fourth natural size. (See p. 609) 



Nat. Mus. 4260, skull Q, type, South Dakota, probably CorralDraw, Tilanotherium zone, lower levels (J. B. Hatcher). This is 

 regarded as the most primitive Allops. The specinaen, which is badly crushed laterally, was at first referred by Osborn to 

 Menodus heloceras, but it differs from Menodus in the more elongate oval section of the horns and the more tapering form of 

 the nasal and in the facts that two distinct incisor alveoli are retained and that the canines are compressed anteroposteriorly. 

 It is therefore considered a very primitive member of the Allops phylum. The species shares much in common with Menodus 

 heloceras (dolichocephaly, elongate grinders, sharp internal and external cingula, etc.) and according to the "group method" 

 of classification would be placed in a primitive genus ancestral to both Menodus and Allops. 



