
No. 428.] PALEOZOIC FISHES. 657 
external aspect; (B), inner aspect of anterior portion of the 
dentary ; and (C), inferior view showing external outline and 
channel separating the dentary portion from the shaft. 
“ Horizon and Locality: — Hamilton Limestone; Andalusia, 
Rock Island County, Illinois." 
(Note. — The specific title which St. John had intended to propose has 
already been applied by Dr. J. M. Clarke! to a gnathal plate from the 
Hamilton of western New York. Moreover, although St. John clearly has 
the priority of discovery, the species which he here recognizes as distinct 
has been described under the name of D. pustulosus? Only one of the 



Fic. 2. — Dinichthys P 

Eastm. Hamilton limestone; Milwaukee, Wis. 
Left gnathal plate. 32. 
illustrations to which he refers is now extant. It is reproduced in the 
accompanying Fig. r, and in Fig. 2 is shown a corresponding dental plate 
belonging to an individual of about equal size from the Hamilton of Mil- 
waukee, the original being preserved in the Milwaukee Public Museum. A 
fragmentary gnathal of D. pustulosus, from the Hamilton of New Buffalo, 
Iowa, is also preserved in the Museum of Comparative Zoólogy at 
Cambridge.] 
1 Bull. U. S. Geol. Surv., No. 16 (1885), p. 17, Pl. I, Fig. 1. 
? Bull. Mus. Comp. Zoél., vol. xxxi (1897), p. 38, Pl. III, Fig. 4; Amer. Nat., 
vol. xxxii (1898), p. 748, Figs. 1,2; Journ. Geol, vol. viii (1900), p. 32, Fig. 1. 

