170 PALEOZOIC FISHES OF NORTH AMERICA. 
Since the date of that report (1875), Mr. J. W. Davis, in a paper pub- 
lished in the Quarterly Journal of the Geological Society of London for 
May, 1879, “On Some Fish Spines and Teeth from the Lower Coal Meas- 
ures,” figures and describes a number of small dorsal spines which should 
evidently be associated with that under consideration. To these he has 
given the generic name of Hoplonchus, and his species is Hoplonchus elegans. 
His specimens come nearer to Ctenacanthus than that from the Cleveland 
shale, as according to his description some of the longitudinal ridges are 
tuberculated near the base. Most of the striz, however, are smooth, and 
the denticles of the posterior border are like those of our specimen, rela- 
tively large and widely spaced. 
CLapopus concinNus, Newb. 
Plate XXI, Figs. 9, 10. 
Cladodus concinnus, N.; Paleontology of Ohio, vol. 2, p. 48, pl. 58, fig. 8. 
Teeth from one-half an inch to an inch in height and breadth; base 
narrow boat-shaped, with pointed extremities; central cone compressed, with 
sharp edges; posterior face flat or gently rounded; anterior strongly 
rounded; both striated; lateral denticles generally two pairs, both striated; 
external pair the larger and divergent. 
This beautiful species is noticeable for its compressed double edged and 
strongly striated cone, its divergent lateral denticles, and its narrow, pointed 
base. It is unusually elegant in form, and is one of the most highly orna- 
mented of all the species of the genus. 
The specimen figured in the Ohio report is much smaller than those 
since obtained by Mr. Terrell, and it therefore gives a false impression in 
regard to the average size. Those now shown are selected from a consid- 
erable number and fairly represent the species. 
Formation and locality: Cleveland shale; Lorain County, Ohio. Col- 
lected by Mr. Jay Terrell. 
Ciapopus TERRELLI, n. sp. 
Plate XXVII, Figs. 5-7. 
Teeth of various sizes, the largest one inch in height and breadth; 
robust; base narrow, boat-shaped, with rounded lateral extremities; central 
