CRUSTACEA. 165 



CERATIOCARIS (?) SIMPLEX. 



PLATE XXXI, FIG. 2. 



Ceratiocaris simplex, Clarke. Bull. U. S. Geol. Surv., No. l(i, Higher Devonian Faunas of Ontario county, 



N. Y., p. 43, pi. ii, fig. 2. 1885. 



The characters of this species are quite obscure, the type specimen being a 

 cast of the internal surface of the cephalothorax. This appears to be bivalvular, 

 oval in outline, the hinge-line gently curved. The anterior extremity is some- 

 what broken, but appears to have been obliquely truncate or slightly notched ; 

 the ventral margin has about the same degree of curvature as the dorsal line, 

 and the posterior extremity is sub-acute. Surface convex, sloping gently to 

 the ventral margin, but much more abruptly to the dorsal line. The margin 

 is distinctly thickened on all sides and was probably somewhat elevated. No 

 evidence of ornamentation is visible. The single valve measures 29 mm. in 

 length by 12 mm. in width. 



Distribution. In the lower shales of the Portage group as originally defined 

 (" Naples beds," of Clarke). Parrish gully, Naples, Ontario county. 



