140 
The American Geologist. 
March, 1896 
of the structure at the distal, apical extremity and the figures 
indicate that the specimen is broken at this point. 
The example received from Mr. Sarle is from the shales of 
the Niagara group at Rochester, N. Y. We shall call it 
Lepidoeoleus sarlei. The single specimen has suffered no 
distortion and has very much the same blade-like form as 
L. jamesi. It has, perhaps, lost one or more of its basal 
plates over the flexed portion of the body, as our specimen 
bears thirteen plates on one side and twelve on the other. 
The thirteenth, however, is terminal and axial, and belongs 
as much to one series as the other. The Cincinnati speci¬ 
men of L. jamesi is stated to bear fifteen plates on each 
side, and in the Lower Helderberg species, L. polypetalus , the 
example described below bears seventeen plates, though it is 
incomplete at both ends, and shows very slight evidence of 
basal flexion. Yet the structure of the best preserved speci¬ 
men indicates that the basal flexion is a normal and not a 
casual feature of the genus. The entire length of the speci¬ 
men of L. sarlei is 23 mm., about twice that of Faber’s L. 
jamesi , and probably not much more than one-half the length 
of L. polypetalus. The structural characters are in general 
harmony with those upon which the genus is based. The de¬ 
gree of overlap of successive plates seems to be greater than 
in Turrilepas and probably amounts to fully two-thirds of 
the entire length of the plate. The exposed portions on the 
lateral surfaces are narrow, ribbon-like bands, while, if the 
curvature of the concentric lines be carried out, the form of 
the plate must be subsemicircular. No isolated plate of the 
species has been met with and that at the base of the specimen, 
shown somewhat obliquely in the figure, is the only one giving 
any suggestion of the full outline. 
The distal or caudal extremity has the following structure: 
The terminal plate on the left side extends beyond that on the 
right side. Viewed from the dorsal side this plate is seen to 
be median and axial as well as terminal. Its back is narrow 
and grooved to the tip, the groove thus begun being contin¬ 
ued forward, enlarging in width, becoming deeper and with 
more elevated edges which are eventual^ lost or obscured 
by the overhanging apices of the plate. Where this dorsal 
furrow is exposed near the caudal extremity oblique lines of 
