WATERLIME GROUP. 
391 
to assign a greater geological range to the Eurypterus; and he remarks : 
“ The range of the genus, therefore, so far as yet known, certainly is 
“ confined between the Ludlow rocks and the base of the Carboniferous 
“ system. Apparently it did not commence to exist so soon as its gigantic 
“ ally, the Pterygotus; but it continued to live on longer, and attained 
“ its maximum of size in beds higher than those in which Pterygotus is 
“ known to have been found 
Thus far our experience in the United States leads us to coincide more 
nearly with the opinion of Sir R. I. Murchison, who regards these peculiar 
forms as having very limited geological range. It appears to us that the 
Old Red sandstone localities cited should be reviewed with the greatest 
care ; and although there could seem to be no doubt but the E. scouleri 
occurs in Lower Carboniferous strata or in Upper Old Red, our science 
would be greatly benefited by a thorough review and revision of the 
whole subject, aided by the light lately acquired in regard to these very 
interesting organisms. 
The few fossils that have been found associated with Eurypterus are : 
A small species of Leperditia, and more rarely a larger one; a single 
specimen, of Discina, and one of Conularia ; and a small species of Lingula 
is not uncommon in the same beds in Western New-York. Associated with 
E. lacustris near Buffalo, Mr. Cobb has obtained a fragment of Pterygotus ; 
a genus for the first time, so far as I know, recognized among our Ameri¬ 
can fossils. 
I have, also, among the collections accompanying the E. remipes from 
Waterville, a fragment showing several articulations with post-oral plate 
and portions of the anterior feet on one side, which differs so far from 
Eurypterus as to induce a doubt as to its generic identity with that fossil, 
and which is probably a Pterygotus or a closely allied form. In the same 
collection there are fragments of a Ccratiocaris; and the collections of 
Mr. Cobb from Williamsville have shown several fragments, with some 
nearly entire but distorted specimens of the same. Besides these, a few 
other organisms are associated with the Eurypterus , the relations of which 
have not yet been determined.' 
* Salter on Eurypterus : Quarterly Journal of the London Geological Society, Vol. xii, p. 235. 
