Loomis — Camels of the Harrison Beds. 



65 



Art. IX. — The Camels of the Harrison Beds, with Three 

 New Species; by F. B. Loomis. 



During the deposition of the Upper and Lower Harrison 

 beds of Lower Miocene age there was probably no more 

 abundant or varied group Of vertebrates in that region than 

 the camels. Already six species belonging to two genera have 

 been described, and in this paper three more will be added to 

 the number; but even then the collectors in that region, judg- 

 ing from the varied toe bones, etc., are confident that there are 

 yet several species to be added. The deposits are typically 

 those of an upland countiw, those of the Lower Harrison being 

 fluviatile, and those of the Upper Harrison, in a considerable 

 proportion at least, eolian. The fauna points in the same 

 direction, being entirely composed of plains types and river- 

 frequenting animals, like the rhinoceroses, Diceratherium and 

 Aceratherium. 



In 1908 both Yale University and Amherst College had 

 parties working together along Muddy Creek and in the 

 " breaks " to the south of the Raw Hide Buttes in Converse 

 Co., Wyo. ; and it is the camel material of these two expedi- 

 tions which is the basis of this paper, the authorities of the 

 Yale Museum having generously loaned all of theirs for this 

 purpose. 



In the Lower Harrison beds the camels which are most 

 abundant belong to the genus Stenomylus, forms characterized 

 by their very hypsodont dentition and slender build. Of these 

 there are three species as differentiated further on. Then one 

 species of Oxydactylus has been described by Mr. Cook from 

 these beds, making four known species. It is in these horizons 

 that there are doubtless several more species. In the Upper 

 Harrison beds two species of Oxydactylus have been described 

 by Peterson, the genus being characterized by a brachyodont 

 complete dentition and elongated limbs. To these will be 

 added two more species of Oxydactylus and one of Protomeryx, 

 which differs from the foregoing by not having the excessive 

 development of limbs and still retaining the brachyodont denti- 

 tion. In both divisions of the Harrison it will be seen that the 

 camels are specialized and further that they are of the open 

 country or plains types. The more generalized genus Pro- 

 tomeryx is strikingly scarce, being only represented by the one 

 species, which in its turn is the slenderest representative of 

 the genus. 



The genus Oxydactylus is the dominant one, containing five 

 different species, the representatives of which are also among 



Am. Jotjr. Sci.— Fourth Series, Vol. XXXI, No. 181.— January, 1911. 

 5 



