1S96.] Geology and Paleontology. .~>1 



oval. Dentition : I 2/ , C V, Pm ?', M y, the third premolar being 

 much reduced. 



Length of skull, condyles to premaxillary border (ap- 

 proximately) 120 mm. 



There are thus six species of Hoplophoncus, disregarding H. strigi- 

 <hns Cope, which being based upon a fragment of a canine exhibiting 

 a peculiar form, is not characterized by any features which refer it to 

 Hoplophoneus rather than any other genus. With the exception of H, 

 cerebralis they are all from the White River. They present an inter- 

 esting series both in the size of the skulls and skeletons. The accom- 

 panying series of femora give an idea of the relative characters of the 

 skeletons of the larger members of the genus as regards size and 

 strength. Unfortunately nothing is known of the skeleton of H. cere- 

 hralif, but judging from the size of the skull it would be the smallest of 

 the series, although probably not much smaller than that of H. oreodon- 

 tis. In restoring the femur of H. occidentalis I am indebted to Dr. 

 Williston for information as to its length. 



The series of skulls figured in outline when taken in connection with 

 the series of femora give an idea of the relative size of the species. The 

 gradation in size is for the most part comparable with the gradation in 

 size of the skeletons. Each species has shown, from careful comparisons 

 and measurements of all the available material, a limited amount of 

 variation, but in no case losing its identity when both the skull and 

 skeleton are taken into consideration.— Geo. I. Adams, Fellow of 

 Princeton College. 



Explanation of Plates. 



Plate I. 

 Fig. 1. — Hoplophoneus cerebralis (after Cope). 



Fig. 2. — Hoplophoneus oreodontis (number 10,515 Princeton Museum). 

 Fig. 3. — Hoplophoneus primaevus (after Leidy). 

 Fig. 4.— Hoplophoneus robustus (number 650 American Museum). 

 Fig. 5.— Hoplophoneus insolens (number 11,022 Princeton Museum). 

 Fig. 6.— Hoplophoneus occidentalis (after Williston). 



All XI 



Fig. 1.— Hoplophoneus occidentalis (Leidy 's type). 



Fig. 2.— Hoplophoneus occidentalis (number 1,047 American Mu 



Fig. 3.— Eusmilus dakotensis (after Hatcher). 



