160 NEW YORK STATE MUSEUM 
from the doublure of the carapace, but no epistoma is formed. The meta- 
stoma is oval in outline, but slightly emarginate in front. The tergites 
and sternites are more or less bandlike and plain as in other genera; the 
male opercular appendage is small, with simple median lobe; that of the 
female long, extending to the third sternite and beyond, consisting of two 
paired and two single members, the paired members forming two pen- 
tagonal basal pieces, and two clawlike terminal pieces. The single imbri- 
cating lobes form the long median part. They are produced into lateral 
points at their posterior extremities. Two curved, interior tubes are 
connected with the female organ. The postabdominal segments are band- 
like rings. The telson is long, spinelike, flat on the dorsal side and carinate 
on the ventral side. 
Several species which have currently been brought under Eurypterus 
are here shown to belong to Eusarcus and to differ in a number 
of characters of generic value, viz, the form of the carapace which is tri- 
angular, the marginal position of the compound eyes, the decrease back- 
ward of the endognathites and the spinosity of all legs, the form of the 
metastoma, which is subtriangular and the broad: and flat preabdomen. 
The differences of Eurypterus from the other genera are well known and 
for the most part manifest. T hey consist principally in the position of | 
the lateral eyes, the absence of distinct facets, the different development 
of the chelicerae and endognathites, the form of the metastoma, of the 
opercular appendages and of the telson. 
The North American species are given in the following list, those 
found in New York being distinguished by an asterisk. The list is in 
ascending order. | 
Lower Stlurtc Upper Silurtc 
FRANKFORT SHALE CLINTON BEDS 
*H. megalops nov. 7 *E. prominens Hall 
*E. pristinus nov. KOKOMO WATERLIME—(=Lockport) 
*EH. ?(Dolichopterus?) stellatus E. kokomoensis Muller & Gurley 
NOU. E. ranilarva nov. 
