DEVONIC FISHES OF THE NEW YORK FORMATIONS 1 35 



Dinichthys dolichocephalus sp. nov. 



Plate 5, ficjure i 



The remains which we propose to describe under this title leave much 

 to be desired in the way of preservation, hence it is impossible to gain more 

 than a superficial idea of the peculiarities presented by the new form. 

 Inasmuch, however, as a number of plates, including the head shield and 

 mandibles, are here found in natural association, and as we have evidently 

 to deal with a form partaking of the characters of both Dinichthys and 

 Coccosteus, some notice of the material seems desirable. Taken in connec- 

 tion with D. h a 1 m o d e u s, from the Marcellus stage, the present species 

 will at least serve to emphasize two facts with which paleichthyologists 

 seem to be unfamiliar. The first of these is that to which we have already 

 called attention, namely, as to the close relations between Dinichthys and 

 Coccosteus ; and the second is that, little by little, we are becoming cogni- 

 zant of a surprising variety of Coccosteuslike forms in the Middle and 

 Upper Devonic, by means of which it may in time be possible to trace the 

 successive stages of evolution leading up from primitive Arthrodires to the 

 gigantic creatures which constitute one of the most remarkable features of 

 late Devonic fish life. 



Naturally one turns first of all to the dentition to determine whether 

 the characters approach those of Dinichthys or Coccosteus, and after that 

 one considers the cranial pattern, sensory canals, and arrangement of body 

 plates. On the evidence furnished by the mandibles, which are the only 

 portions of the dentition preserved, one is led to decide unreservedly in 

 favor of an association with Dinichthys ; on the evidence of the head shield, 

 and all of the body plates excepting the clavicular, the decision would be in 

 favor of Coccosteus. We are obliged, therefore, to recognize the transi- 

 tional nature of the species here represented, and as insufificient characters 

 are offered for the erection of a new genus, it may be provisionally assigned 

 to Dinichthys, 



The mandibular rami are unusually long and slender, their total length 



