THE EURYPTERIDA OF NEW YORK 261 
The question of the phylogenetic relation of Dolichopterus to Stylo- 
nurus, Drepanopterus and Eurypterus has been fully dealt with in the 
introductory chapter to which we here refer. 
Besides the three species of Dolichopterus from the New York rocks 
thus far mentioned, the Bertie waterlime at Litchfield and the Shawan- 
gunk grit at Otisville have each furnished a type represented only by the 
carapace; D. testudineus and D. otisius; and the Frankfort 
shale has afforded the fragmentary remains designated D. frankfort- 
ensis and D. latifrons. 
From the waterlime beds of Litchfield we have a swimming leg, which 
possesses in general the characters of Dolichopterus but has a greatly 
differing palette or terminal segment. The latter is elongate oval and 
strikingly resembles the palette of Pterygotus. As the palette in Ptery- 
gotus is the eighth segment, while that of Dolichopterus is the ninth, 
this similarity can hardly be more than the result of convergence. This 
limb is as far different from that of the genotype, D. macrochirus, 
in one direction, as that of D. stylonuroides is in another. 
In this the relative compactness and strength of the swimming leg. of 
D.macrochirus is carried to extreme, in the other the tendency of 
D.macrochirus to the development of broad lobelike appendages. 
These few species together indicate a greater variability in the char- 
acters of this genus than is shown by other genera. 
The genus is at present represented by seven American and two European 
species, V1Z: 
. macrochirus Hall . stylonuroides nov. 
. testudineus nov. 
. laticeps (Schmidt) 
. sp. Holm! 
. frankfortensis s0v. 
. latifrons nov. 
OOU0UOD 
. Siluriceps nov. 
. otisius Clarke 
OOUU YU 
1 As before stated, Holm recognized the probable occurrence of this genus in the 
Baltic provinces by the observation of two metastomes, one of which he has referred 
to Eurypterus laticeps Schmidt. This species is known only by its cara- 
pace which in outline, broad rim, large eyes and ornamentation is very suggestive of 
the Stylonurus-Dolichopterus group. He also referred an operculum with female 
