AECHAEOTHERIUM. 57 



deeper; tlie post-glenoid tubercle is shorter and relatively very much more robust; 

 and the os tympanica, instead of being slightly swollen at the inner termination of 

 the vaginal crest of the auditory process, as in the former, is developed into a bulla 

 relatively as large as in the Californian Deer. 



In Eucrotaphus Jachsoni (Fig. 6), the auditory bulla forms a large, simple mam- 

 raillary eminence, which abuts against the sphenoid bone anteriorly and the para- 

 mastoid process posteriorly, and rests with its base internally upon the margin of 

 the basilar process and the conjunction of this with the sphenoidal body, and is 

 outwardly continuous with a ridge the homologue of the vaginal process. 



In Eucrotaplius auritus (Fig. 3), the auditory bulla has the same connections as 

 in the former, but in addition rests against the post-glenoid tubercle; and it is rela- 

 tively slightly larger, and laterally compressed. 



Fam. 2. — Paridigitata Oedinaria. 



Gen. ARCHAEOTHER11JJTI, Leidt: {Entdodmi? Aymard.) 



Archaeotherium is a remarkable genus of suilline ungulata combining apparent 

 ruminant and carnivorous characteristics. In the form of its superior molar teeth it 

 exhibits an affinity to the extinct Ghoeropotamiis, Cuvier, and in a less degree to 

 the Hyracotlierium, Owen; but, judging from a sketch in Gervais's Zoologie et Pale- 

 ontologie Frangaises,^ of the upper molars of Entelodon, Aymard, it approaches 

 this much more nearly than either the former. Indeed, the posterior five 

 superior molars of Entelodon and Archaeotherium are so alike in relative position, 

 proportion, and form, that I consider it doubtful whether the latter is distinct from 

 the former; but not having an opportunity of examining the original descriptions 

 and figures ,of Aymard,^ nor of extending the necessary comparisons, I have pro- 

 visionally retained the generic name originally proposed. 



Archaeotherium Mortons, Leidy. 



(Plate VIII ; IX ; X. Figs. 1-7.) 



Archaeotherium Mortoni, Leidy: Proc. Acad. Nat. Soi., 1850, v. 92; Owen's Rep. of a Geol. Surv. of Wise., 558. 

 Archaeotherium [Entelodon?) Mortoni, Leidy: Owen's Rep. etc., refer, to Table X. 



The species Archaeotherium Mortoni was established in the Proceedings of the 

 Academy of Natural Sciences (Vol. V. p. 92, for 1850), upon a fragment of a face 

 containing the third and fourth premolars of the left side, presented to the Academy 

 by Mr. Alexander Culbertson. 



Later, I have been enabled very greatly to extend our knowledge of this animal 

 by the investigation of several interesting specimens in the collection of Dr. Owen. 



One of these is a portion of the fiice very much mutilated, of an adult individual, 



^ P. 102, p. 2, 26, fig. 12. 



" Mem. Soc. Agric. Sci., etc., du Puy, t. xii. p. 240; 1848. Gervais. 



