96 WHITE AVES ON FOSSIL FISHES, ETC. 



and presumably two rows of short, conical booklets, whieb curve obliquely downward. 

 Anterior margin tbin, straigbt or gently convex, and unarmed. Surface marked on eacb 

 side by from fifteen to twenty longitudinal ribs vvbicb swell out at regular intervals of 

 about one-tbird of a line apart, into subaugular, equidistant nodes. 



Lengtb of tbe largest spine collected, about two incbes and a balf ; maximum breadtb 

 of tbe same at tbe base, about tbree quarters of an incb. 



Tbe few spines of this species collected by Mr. Foord are all partly imbedded in tbe 

 matrix, so tbat tbe grooving of tbe posterior margin is bidden from view, and only one 

 row of booklets is exposed. 



HOMACANTHUS GKACILIS, N. Sp. 



(Plate X, tig. 4.) 



Homacanthus, Sp. Undt. "VVbiteaves, 1881. Can. Nat. and Quart. Joiiru. So., N. S., Vol. 

 X, p. 99. (Compare H. arcuatus, Agassiz, Poiss. foss. du Vieu.x Grés Rouge, p. 

 113, tab. .33, figs. 1-3). 



Fin spine ratlier large (for a Homacanthus), compressed laterally, distinctly curved, 

 slender, elongated and tapering very gradually from a narrow base to an apparently ob- 

 tuse point. Upper portion of the posterior margin armed witb one or moi"e rows of 

 conical booklets, wbicb curve obliquely downwards. Surface ornamented by about 

 seven longitudinal ribs on eacb side, wbicb are minutely and obliquely striated. 



Lengtb of tbe actual specimen (in which tbe apex of the spine is broken off) 

 twenty-three millimetres. Breadth of tbe same, at the base, about six millimetres. 



Only one imxierfect and badly preserved specimen was obtained, one side of which 

 is buried in tbe matrix. It differs from tbe spines of Ctenacanthus latispinosus in its more 

 slender proportions, more arcuate form and apparently also in its surface ornamentation. 

 As far as can be ascertained at present, this spine appears to be very similar to the H. 

 arcuatus of Agassiz, in almost every respect but that of size, the Campbellton sx^ecies 

 being much the larger of the two. 



