164 [September, 



ceded by a small curved, conical caniue. The anterior three pre-moLars possess 

 a large outer lobe, and a postero-internal column, which is nearly obsolete in 

 the first of the series, and is best developed in the last. The fourth pre-molar 

 has a symmetrical pair of lobes as in ordinary ruminants. 



In a specimen of the lower jaw belonging to L. major ^ and containing several 

 true molars, there are also three pre-molars. The last of the latter had been 

 but a short time protruded. Its crown, in the general form, is like the outer 

 part in the corresponding tooth of the deer. The antepenultimate pre-molar 

 has a triliedral crown, of which the inner and posterior sides are depressed. 

 The intermediate pre-molar belonged to the temporary series, and has its crown 

 nearly worn away. The specimen of the lower jaw indicated proves that the 

 fragment of a lower jaw containing several pre-molars, the canine, and incisive 

 alveoli, previously referred to L. decora, does not belong to that genus. 



Comparative measurements of L. decora and L. major are as follows : 



L.decora. 

 Series of seven upper molars, - - - - 25 lines 



" upper true molars, - - - - 14 " 



" lower " " - _ - - 15 " 



L. major. 

 32 lines. 



20 " 



21 " 



2. Protomertx Halli, Leidy. 



Founded upon a fragment of the lower jaw, containing alveoli for three incisors 

 to one side of the symphysis, and followed immediately by the canine. The 

 latter is small and has a laterally compressed, obtuse crown, somewhat resem- 

 bling the upper canine of the Llama. Succeeding the canine after a short in- 

 terval is the first pre-molar, with the crown broken off, but which apparently 

 had the same form as in the canine. After another interval of about one-third 

 of an iuch, there are two pre-molars, inserted by two fangs, and having a broad, 

 laterally compressed, pyramidal crown. 



The animal is most probably a ruminant, partaking of the characters of the 

 camel and the suiline families. 



Specimen obtained by Dr. F. V. Hayden, at Bear Creek, Nebraska Territory. 

 Formerly supposed to belong to Leptauchenia decora. 



The species is dedicated to Prof. James Hall, the eminent palaeontologist. 



3. Oreodon major, Leidy. 

 Ancient Fauna of Nebraska, 55. 



Having the opportunity of examining an entire skull of Oreodon major, in the 

 St. Louis collection of Nebraska fossils, obtained by Dr. Hayden, I find it is 

 really a distinct species, being characterised, not only by its larger size than 

 the other described species, but from its possessing large inflated tympanic 

 bones, which is not the case in 0. Culbertsonii and 0. gracilis. This latter cha- 

 racter might be supposed to be generic, but it is the only important anatomical 

 feature in which 0. major differs from the other species. 



Comparative measurements of the skull of the three species are as follows : 



Oreodon major, ... length 8| in. . . - breadth 5J in. 



" Culbertsonii, - - " 1\ in. - - - " ^ in. 



" gracilis - - - " 5 in. - - - " 3" in. 



4. Agriochcerus major, Leidy. 



A larger species than A. antiguvs, indicated by a single inferior true molar. 

 It is the first or second, and measures three-quarters of an inch antero-poste- 

 riorly and half an inch transversely. 



Specimen in the Nebraska collection made by Dr. Hayden, for the St. Louis 

 Academy of Sciences. 



5. Entelodon ingens, Leidy, 



A huge species, indicated by several mutilated canines, the anterior extremity 

 of a lower jaw without teeth, and the crown of an inferior molar tooth. The 

 chin of the fragment of a jaw is 4^ inches in depth and 5 inches in breadth at 



