E. L. Troxell — American Bothriodonts. 327 



like that of P'^ and on the lower jaw there is a tubercle 

 under P4 like those of the entelodonts. In few respects 

 does this genus resemble even the Old AVorld bothrio- 

 donts, and it is widely different from those of the western 

 hemisphere. 



Heptacodon Marsh. 



(Fig. 1.) 



Genoholotype, H. curtus Marsh. Upper Oligocene (Protoceras beds), 

 Phinney, South Dakota. 



The original description of H. curtus is as follows -^ 



''A very perfect last upper molar, which may be taken as the 

 type, is shown natural size in the accompanying fignres. Its 

 crown is composed of the same main elements as in the corre- 

 sponding tooth of Hyopotamns, but all the five cusps are much 



Fig. 1. — Heptacodon curtus Marsh. Holotype. Cat. No. 11803, Y. P. M. 

 Crown, side, and front views of M^. After Marsh. Nat. size. 



less elevated. In addition, the basal ridge of the outer margin is 

 swollen into two high pointed cusps, making seven in all, and this 

 has suggested the generic name. 



"Of the outer cusps, or buttresses, the anterior one is the 

 larger, and is situated well forward and partly outside of the main 

 body of the crown. The antero-median cusp is well developed, 

 triangular in outline, and situated somewhat in advance of the 

 other two anterior cusps. . . . The two interior cones are con- 

 nected near their margins by a low ridge, and their summits are 

 joined by a high outward- curved ridge, which extends nearly to 

 the centre of the crown. The crown itself is very short, consid- 

 erably shorter than in the molars of Hyopotamns. 



"The animal thus indicated, which may be called Heptacodon 

 curtus, was somewhat larger than a sheep. The known remains 

 are from the upper Miocene of South Dakota. ' ' 



This specimen, probably the second upper molar (see 

 fig. 1) , as shown by wear on the posterior side, is markedly 

 distinct from any other specimen at hand and bears 



" 0. C. Marsh, This Journal (3), 47, 409, 1894. 



Am. Jour. Sci.— Fifth Series, Vol. I, No. 4.— April, 1921. 

 22 



