THE EURYPTERIDA OF NEW YORK 155 
To sum up the foregoing distinctive features in Strabops, we find that 
the lack of differentiation of the parts of the abdomen and the general 
primitive aspect of the form, together with the high geologic age of the 
genus warrant its recognition as distinct from Eurypterus, though it is 
manifest that the form is very similar thereto. 
Genus EURYPTERUS DeKay 1825 
The genus Eurypterus embraces not only those representatives of the 
order Eurypterida longest known and most completely understood, but it 
also surpasses all other genera in the number of species and in geological 
and geographical range; it represents the most vigorous and the most 
typical genus of the order, although it does not contain the giants of the 
group. It is therefore very proper that it should have given its name to 
this remarkable order of the class Arachnida. 
The genus was erected by James E. DeKay in 1825 for the most com- 
mon of the New York species, viz, Eurypterus remipes. The 
organization of the body of Eurypterus was first elucidated and elaborately 
described by Nieszkowski [1858] and James Hall [1859]; the former basing 
his observations on the finely preserved material from the island of Oesel 
in the bay of Riga, Russia, the other on that from the waterlimes of New 
York. Hall described seven supposed species from the New York rocks, 
viz, E.remipes, microphthalmus, lacustris, robus- 
tus, pachychirus, dekayi, pustulosus, to which a 
few have been added since from the rocks of this State, viz, E. (?) 
prominens Hall and Clarke [1888], E. pittsfordensis Sarle 
[1902] and E. maria Clarke [1907]. A form from the Guelph dolomite 
of Canada (E. boylei Whiteaves), two from the waterlime of the same 
horizon at Kokomo, Indiana (E. kokomoensis Miller & Gurley 
and E. ranilarva nov.) a small number of species from the Carbonic of 
Illinois and Pennsylvania (E. mazonensis, E. mansfieldi, 
E. pennsylvanicus, E. potens, E. stylus and E. ap- 
proximatus); and the species E.? megalops, E. pristinus 
