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 Bufialo, Mr. Cobb has obtained a fragment of Pterygotus ; 

 a genus for the first time, so for 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 Greologlcal Society, Vol. xii, p. 235. 



