DEVONIC FISHES OF THE NEW YORK FORMATIONS 53 



Bothriolepis coloradensis Eastman 



1904 Bothriolepis coloradensis C. R. Eastman. Am. Jour. Sci. [4] 18: 254, 

 text fig. 2, 4 



This, the largest known American species of Bothriolepis, is chiefly 

 interesting on account of its geographical and geological occurrence, and 

 for the evidence it furnishes regarding Asterolepid distribution. Although 

 the length of the appendages has not been determined in this form, the 

 general configuration of the ventral surface, and particularly the lozenge- 

 like form of the ventromedian plate, sufficiently warrant its reference to this 

 genus. Its relations seem to be rather with the Canadian than with either 

 of the Chemung-Catskill species occurring in the eastern United States. 

 Add to this the fact that no Asterolepid remains are known from the Upper 

 Devonic horizons of the middle west, although other Chemung forms are 

 present in abundance, it is difficult to trace the line of migration so as to 

 connect the Rocky mountain species with those in New York and Pennsyl- 

 vania. On the assumption that the former is a European immigrant, two 

 other routes are available, one lying to the northward, by way of Canada, 

 and the other to the southward, around the end of the Appalachian chain. 

 A further discussion of this question may be reserved for a subsequent 

 section of this memoir. 



In the original description of this species, two figures were introduced 

 for the purpose of comparison with Scottish specimens which bore the 

 designation of Bothriolepis major, and were reputed to have been 

 derived from the well known locality southward of Elgin. Recently, a 

 more attentive examination of these specimens ' and of the matrix in which 

 they are inclosed has led the writer to believe that they could not have 

 been collected at Elgin, but most likely from the Upper Old Red sand- 

 stone of the immediate vicinity of Nairn. Now these Nairnshire plates, 

 which in former years were universally known under the name of P t e r- 



' The median ventral in particular is broader and more ovately lozenge-shaped than 

 in Bothriolepis major, and the specimen shown with all the ventral plates in 

 apposition is one of the best ever found of this species. 



