40 PALEOZOIC FISHES OF NORTH AMERICA, 
MAcH@®RACANTHUS PERACUTUS Newb. 
Plate XXIX, Figs. 6, 67. 
Macheracanthus peracutus N.; Bull. Nat. Inst., loc. cit. 
Palxontology of Ohio, vol. 1, p. 305, Pl. X XIX, Fig. 6. 
Spines five to six inches in length, seven to eight lines wide; point 
and edges very sharp; wings nearly equal; central axis on the upper sur- 
face forming a sharp and narrow carination, below a higher but more 
rounded ridge. 
This is perhaps the species most common in Ohio. _ It will be recognized 
by its small size, the acuteness of its point and edges, and by the angular 
ridge of the median line above and below. It is the species referred to 
in the generic description and that which furnished the figures employed 
there to show the paired character of these spines. The average size and 
appearance are well shown in the illustration cited above. 
Formation and locality: Corniferous limestone; Delaware and San- 
dusky, Ohio. 
MacH@®RACANTHUS SULCATUS Newb. 
Plate X XIX, Figs. 5, 5°. 
Macheracanthus sulcatus, N.; Bull. Nat. Inst., loc. cit. 
Paleontology of Ohio, vol. 1, p. 305. 
Spine four to eight inches in length, six to ten lines wide; upper sur- 
face smooth, with a strong and sharp carination along the axis; wing of 
convex side widest; opposite wing narrow, and exhibiting a strong marginal 
sulcus, giving it a double edge; under surface of axis rounded, with several 
longitudinal sulci and carine and with oblique angles at sides. 
At the time of writing the description of this species I had no suffi- 
ciently good specimen to furnish a satisfactory.figure. Since then I have, 
however, found better specimens in the collection of the late Dr. Mann, now 
belonging to the Ohio Wesleyan University at Delaware, Ohio, and a num- 
ber of more or less well-preserved spines have been sent to me for examina- 
tion from Canada. It would seem that the sharks that carried these spines 
were more numerous in those portions of the Corniferous sea which covered 
