XVII. DESCRIPTION OF THE TYPE SPECIMEN OF 

 STENOMYLUS GRACILIS Peterson. 1 



By O. A. Peterson. 



Since the first account of this aberrant cameloid was issued the 

 remainder of the type specimen has been cleared from the matrix 

 and is here more fully described in connection with a number of illus- 

 trations. In view of the additional material which has been collected 

 recently in the same locality and geological horizon (the lower Harri- 

 son beds of Nebraska) by different field parties it is thought that a 

 more detailed description of the type, especially the cervical vertebrae, 

 the limbs and the feet, may be of interest and assistance to the student. 



Stenomylus Gracilis Peterson. 

 (Type No. 1610, Carnegie Museum Catalogue of Vertebrate Fossils. ) 



The Skull. 



Some characters of the skull are, as has been stated on pages 41-43 

 of this volume, entirely different from any cameloid living or extinct. 

 Thus, the large size and anterior position of the posterior nares with 

 relation to the pterygoids (see Plate XII), the hypsodont, elongated 

 and narrow molars, the high position of the eye (the anterior border 

 of the orbit is on a vertical line with the posterior face of m 3 when 

 the skull rests on the paroccipital processes and the dentition), and 

 the incisiform lower canine and first premolar, which form a continu- 

 ous series with the incisors, are characters most unusual ; while the 

 skull is otherwise quite like that of the Miocene camels generally. 



In my first description (/. c. , p. 42) of the skull I stated that the 

 skull has no sagittal crest, which is incorrect, since I was not then 

 aware of the short and rather broad eminence of the parietals immedi- 

 ately anterior to the occiput on account of the damaged condition of 

 the skull in this region. The general arrangement of the base of the 

 skull back of the pterygoids is not unlike that of Lama huanaco. In 

 fact the general contour of the entire skull seems to be unusually 



1 Annals of the Carnegie Museum, Vol. IV, No. I, pp. 41-43, PI. XII, 1906. 



286 



