BUFFALO SOCIETY OF NATURAL SCIENCES 39 



median line. Eye surrounded by a sclerotic ring composed of four 

 segments. Mandible of the usual Dinichthys type; distinguished by 

 the great distance between the beak and the secondary cusp, the latter 

 being situated toward the middle of the cutting margin. 



Remarks. — ^This species is one of the largest dinichthyids known. 

 It can be compared in size only with Dinichthys terrelli of the 

 Cleveland shale of Ohio, from which, however, it is strongly differ- 

 entiated. It proves that the Ohio dinichthyids were not the only 

 large Arthrodires that existed in late Devonic times, but that coevally 

 with them there lived in the Portage sea of New York, a Dinichthys 

 equally huge and powerful. 



The following is a detailed account of the plates displayed by the 

 type specimen : 



Cranial shield (fig. 9).— The head is fairly well-per served, most of 

 the bone being present, and the sutures and lateral lines can be clearly 

 made out. The only parts missing are the rostral and a portion of the 

 right side. Owing to the favorable conditions of its fossilization, in a 

 concretion, the head is but little crushed down, and shows considerable 

 arching from side to side. 



Its most noteworthy feature is its narrowness anteriorly (com- 

 pare figs. 9 and 10), so that when viewed from above it appears 

 much more triangular than the cranial shield of D. terrelli, or in fact 

 that of any other species known. 



The median occipital element is very short antero-posteriorly, but 

 extremely broad, being greatly extended laterally at each side; an- 

 teriorly it is divided into three short lobes, a median one and a some- 

 what narrower one op either side of it. 



Another pecuHarity of the head shield is to be found in the direction 

 of the preorbital canals. In all species of Dinichthys thus far known, 

 these canals have near their anterior extremities, in the region of the 

 rostral element, a secondary curve, concave toward the median line. 

 In the present species there are no such secondary curves, but instead, 

 the anterior moieties of these canals curve outward toward the antero- 

 lateral angles of the head and terminate at the rounded angles anterior 

 to the orbits. 



Measurements cm. 



Length in median line, with allowance for missing rostral 55 



Width across posterior angles of orbits^* 32 



Width across angles of marginals^^ 70 



^ Based on the half preserved. 



