100 THE CANADIAN NATURALIST. [Vol. X. 



portion of the posterior margin armed with one or more rows 

 of conical hooklets, which curve obliquely downwards. Surface 

 ornamented by longitudinal ribs, with fine oblique striations. 



Length about 17 lines, breadth at base about 3 lines. 



Only one imperfect and badly preserved specimen was obtained, 

 one side of which is buried in the matrix. It differs from the 

 spines of Ctenacanthus latisjnnosiis in its more slender propor- 

 tions, more arcuate form, and apparently also in its surface orna- 

 mentation. As far as can be ascertained at present this spine 

 appears to be very similar to the II. arcuatus of Agassiz, in almost 

 every respect but that of size, the Campbellton species being 

 much the laroer of the twu. 



Crustacea. 



Pterygotus. Sp. Undet. 



The occurrence of this genus at Campbellton is indicated by a 

 fragment shewing the characteristic sculpture of semi-circular 

 plicae, — and by a single ramus of the chela oF an antenna, which 

 must have belonged to a very large species. This ramus, which 

 is npt quite perfect at cither extremity, is about two inches and 

 a quarter in length, and nearly half an inch in breadth at its 

 largest end. It bears on its inner margin four or five unequal- 

 sized, but comparatively large teeth, one of which is of much 

 greater dimensions than the rest, — with a number of smaller ones 

 between them. All the teeth are compressed and longitudinally 

 striated : most of them are ovate-lanceolate in outline, the basal 

 portion being slightly constricted, — but some of the small ones 

 are simply conical. 



Mollusc A. 



Cyclora valvatlformis. Sp. Nov. 



Shell very small, depressed turbinate, broader than high, 

 spire much depressed : whorls three and a half, ventricose, 

 rounded, increasing very rapidly in size, so that the greater part 

 of the shell is formed by the last one, sutures deep ; umbilicus 

 between one-tliird and one-fourth of the diameter of the body 

 whorl, deep in the centre and rounded at the margin. Mouth 

 nearly circular but slightly angular posteriorly, next to the 

 suture ; lip thin and somewhat spreading. Surface nearly 

 smooth, marked only by a few faint striae of growth. 



