172 NEW YORK STATE MUSEUM 
suggestive distinctive character appears to us to be the great difference 
in the relative sizes of the compound eyes. In E. fischeri they reach 
about one third the length of the carapace, but in both E. remipes 
and E. lacustris they are but one fifth or less of the length of the 
carapace. For this reason E. fischeri makes a rather youthful im- 
pression when compared with our forms. Altogether, the differences are | 
so small that Schmidt’s suggestion that they are but geographical varieties, 
is fully supported. 
The relations of E. remipes and E. lacustris are described 
under the latter species. It may be here stated that the two are more 
closely related to each other, than either of them to E. fischeri, 
indicating that they had but lately separated. Their differences rest 
mainly in the shape of the carapace and they are duplicated by those 
between E. fischeri and E. laticeps, two forms associated 
in the same (Baltic) rocks. | 
The E. pittsfordensis described by Sarle from the Pitts- 
ford shale, is also very closely relatedto E. remipes and lacustris, 
indeed is hardly more than a mutation and therefore undoubtedly a direct 
ancestor of the two later Bertie waterlime species. 
Several of our specimens of E. remipes are so favorably pre- 
served that they present features not observed before. The most important 
of these is that represented in plate 6, figure 6, which comes from a 
porous bed of coarse dolomite at Morganville, N. Y., in which the integu- 
ments are but little or not at all flattened. It shows a distinct glabella, 
corresponding in form and extension to that of Limulus and obviously 
due to the same causes. The same specimen also exhibits a deep furrow 
surrounding the lateral eyes and an obscure broad ridge connecting the 
latter and bearing the ocelli. The frontal slope is even and uniform and 
a narrow flat or slightly depressed border is found inside the beveled edge. 
Another partially compressed specimen [pl. 6, fig. 5] exhibits the glabella 
and a broad smooth border, corresponding in extent to the underlying 
‘frontal membrane of the underside of the carapace. 
