64 
PALEONTOLOGY Of NEW-YORK. 
impossible, therefore, to know precisely what the external characters of the shell are, until we 
have more perfect specimens. 
Fig. 9 a. The specimen, natural size. 
Fig. 9 b. The crenulated hinge-line, enlarged. 
Position and locality. This shell, with Leptcena orthididea and L. depressa , occurs in shaly 
laminated sandstone highly charged with oxide of iron, associated with the iron ore beds in the 
town of Kirkland, Oneida county. {State Collection.) 
Genus CHONETES (Fischer). 
This genus has the same form as Leptcena, and is distinguished principally by a row of 
tubular spines on the margin of the dorsal valve bordering the area. 
450. 1. CHONETES CORNUTA. 
Pl. XXI. Fig. 10 a-/. 
Strophomena cornuta. Hall, Geol. Rep. 4th Dist. N. York, 1843. 
Chonetes cornuta. De Koninck, Recherches sur les animaux fossiles, 1847, Part 1, pag. 200, 
pl. xx, fig. 3 a, b. 
Shell semicircular ; surface covered with fine equal striae, which are equal to the spaces be¬ 
tween them; striae round, straight, bifurcating; upper margin of the dorsal area with three 
tubes or spines on each side of the beak •, spines oblique or divergent below, curving inwards 
at the middle and upper parts, outer ones largest; area extremely narrow; interior surface 
striato-punctate as in Lepte:na. 
This shell bears some resemblance to Chonetes lata (Leptcena lata), Sil. System, pl. 5, fig. 
13 ; but a comparison of specimens has shown them decidedly distinct species. 
This species is more flat than the small one in the Corniferous limestone and Hamilton 
group, which it resembles. It is evidently very limited in its geological as well as geographical 
range. It is commonly seen in the form of casts, the shell being extremely thin and usually 
separated; and the spines are often removed with the shell, so that it becomes necessary to 
rely on the form of the shell, striae, etc., to distinguish the species. 
Fig. 10 a, b. Two specimens of the natural size (ventral and dorsal views), having the spiniform 
tubes attached. 
Fig. 10 c. A small fragment of green slate, with several valves upon the surface, some of them 
destitute of spines. 
Fig. 10 d. The dorsal valve enlarged, showing its appearance when magnified to double the 
natural size. 
Fig. 10 e, /. Enlarged portions of casts of the hinge and dental processes of the dorsal and ventral 
valves, as seen under a magnifier. 
