28 THE CANADIAN NATURALIST. [Vol. X. 



the genus Ptericlithys, which, at this locality, seems to be repre- 

 sented by only one species, the P. Canadensis. Some of these 

 are nearly perfect and want only the fins proper and the tail, 

 while others are mere isolated plates or detached portions of the 

 pectoral spines. The new material obtained by Mr. Foord shows 

 that the cranial plates of P. Canadensis were furnished with 

 curious appendages, which will be described more in detail a 

 little farther on. In addition to these specimens of Pterichthi/s, 

 there are examples of eight or nine species of fossil fishes in the 

 collection, belonaino; to at least seven genera. The followino- is a 

 brief description of the cranial appsndnges of the Canadian Pter- 

 ichthys and of the characters by which most of the other species 

 may be distinguished, including the definition of a supposed new 



genus. 



Pterichthys Canadensis. 



One specimen of P. Canadensis shews that the species had 

 two labial appendages, or barbels, attached to the front margin 

 of the head, though, unfortunately, the terminal plates of the 

 anterior extremity of this specimen are so much distorted that 

 it is scarcely possible to ascertain to which of them the barbels 

 were attached. These barbels are almost exactly similar in 

 shape to those represented by dotted lines in the ideal repre- 

 sentation of the genus Pterichthys on Plate 6, fig. 1, of the 

 " Monographic des Poissons Fossiles du Vieux Gres Rouge," 

 which Agassiz claims to have seen in his P. latus, — but in 

 P. Canadensis the barbels are very close together at their bases. 



In two specimens of a Pterichthys from the red beds at the 

 summit of the series, both of which are probably referable to 

 P. Canadensis^ two remarkable, flattened-conical dermal pro- 

 cesses are clearly visible on the helmet, one on each side of the 

 orbital cavity. One of these specimens measures four inches in 

 length, exclusive of the tail, of which, as usual, not a vestige 

 remains ; and in this individual the dermal processes on the 

 helmet are half an inch Ions; and two lines and a half broad 

 near their base. Posteriorly, each process appears to fit into the 

 angle formed by the junction of the " prelateral " with the 

 " nuchal " and '' post lateral " plates of Prof. Owen. Anteriorly, 

 they are each directed obliquely outwards and forwards across 

 the " prelaterals," which they partly cover. They taper gradu- 

 ally Irom their base to an obtuse point, are ornamented with a 

 sculpture precisely similar to that of all the other plates and are 

 pressed close to the surface of the helmet. 



