OEISKANT FAUNA OF BECKAFT MOUNTAIN 21 



to the same species ; for in Ph. braziliensis, of the Maecuru Lower 

 Devonic, another species very closely similar to Ph. anceps, the 

 glabellar furrows may be all well displayed on the internal cast. 1 



The three species above mentioned are alike in the small size of the 

 cephalon, having the same dimensions in all specimens observed, in the 

 rounded genal angles, the firmness of the union of cranidium and cheeks, 

 separated specimens being very unusual, the peculiar dalmanitiform 

 aspect of the glabella and its slight median angulation, the small eyes 

 and smooth surface. Though the other parts of the species are not 

 known, yet the cephalon indicates the intermediate nature of these 

 species between the genera Phacops and Dalmanites, and doubt- 

 less when the rest of the body has been found, it will express similar 

 relations. 



The existence of expressions of this type of structure in the Lower 

 Devonic of the Amazons (Maecuru), of Cayuga, Ontario, at Becraft 

 mountain and nowhere else, so far as known, is a fact of significance 

 in the correlation of these faunas. 2 



Phacops logani Hall 



Plate 1, flg. 1-5 



1892. Phacops sp. nov. Clarke, op. cit. p. 412 



In the notice above cited I suggested the similarity of the speci- 

 mens of Phacops here found to Phacops logani of the Hel- 

 derbergian and Ph. p i p a of the Onondaga limestone. Restudy of 

 the material has convinced me that the fossil is not to be distinguished 

 from the former. Though the species is of frequent occurrence, the 

 specimens are generally somewhat distorted cephala and pygidia, and few 

 entire examples have been observed. Such distortion generally gives a 

 too pointed, subpentagonal form to the glabella and a too narrow and 

 elongate form to the pygidium. The characteristic traits of the species 

 Ph. logani are these : the glabella is relatively narrow and strongly 



1 See Archives do museu nacional do Rio de Janeiro, v. 9, pi. 1, fig. 1, 2. 

 2 The writer has recently obtained specimens representing the same type of structure 

 in the Gaspe sandstone at Gaspe Basin Quebec. 



