ADDITIONS AND CORRECTIONS. 
353 
724. 2. CORNULITES —— (sp.?). 
Plate LXXXY. Figs. 13 - 16. 
The specimens here figured preserve the outer covering and surface marking in a very 
good degree, and from this circumstance present some characters not usually observed in 
species referred to this genus. The annulated character is less conspicuous, and in some 
individuals scarcely an important feature. 
The specimens for the most part preserve some appearance of gentle annulations, which 
are marked with conspicuous waving strise crossed by finer longitudinal ones : the latter 
are often partially or entirely obliterated. In addition to the annulations mentioned, the 
surface often presents waved irregular elevations which leave the broader rings very 
inconspicuous. 
In figs. 13 and 15, the limits of the successive rings, so well marked in the cast, are 
scarcely visible; while in 14 and 16, they become prominent : the latter figure is com¬ 
pressed towards the larger extremity. 
Fig. 17 represents an enlargement of the longitudinal stride. 
One or two of these specimens are hollow; preserving, within the thin striated co¬ 
vering, a series of thick and strong annulations : they were originally hollow bodies, 
apparently without septa or divisions of any kind. 
NOTE A. 
TRACKS OF GASTEROPODA AND CRUSTACEA IN THE CLINTON GROUP (Pag. 26-37). 
Since this volume has been printed, I have had an opportunity of seeing many markings 
of the kind described in these pages, together with others of different character. In the 
summer of 1850, in company with Mr. J. D. Whitney of the U. S. Geological Survey of 
the Lake Superior District, I traced the continuation of the Clinton and Niagara groups 
northwestwardly along the shores of Lakes Huron and Michigan. There, on the peninsula 
of Green Bay, markings of similar character were found upon the surfaces of arenaceous 
layers of the Clinton group. Among these are two forms differing from any described in 
this volume, as well as from each other*. One of these consists of simple parallel cutting 
lines which are more deeply impressed at one extremity, and, continuing for a greater or 
less distance, become gradually less deeply marked, and finally terminate, to be repeated 
in the same direction over a considerable extent : these I have regarded as due to crus- 
* These I have described in the Report of Messrs. Foster and Whitney, U. S. Geologists of the Lake Superior 
Land District. 
