THE EURYPTERIDA OF NEW YORK 413 
adaptation to particular marine conditions. Similar stability of the 
eurypterids is also suggested by the identity or extremely close relation- 
-ship of the species in the Shawangunk grit at Otisville and the possibly 
older beds at the Delaware Water Gap and Swatara Gap [see p. 417] in 
Pennsylvania; and again in the probably somewhat younger McKenzie 
formation of Pennsylvania [see p. 88], and finally also by the continuation 
of the same genera apparently from the Ordovicic, but surely from the 
Siluric into the Carbonic. The eurypterids are then, as a rule, to be 
accorded but little value for purposes of correlation. 
The following species are quite obviously but a meager part of the 
eurypterid fauna of the Normanskill stage, and future discoveries, now 
that the attention of collectors is directed to these interesting fossils, will 
undoubtedly add much to the list. As in the Schenectady shale the generic 
determinations are entirely provisional, as but few legs and telsons have 
been found in connection with the carapaces and fragmentary abdomina. 
Eurypterus chadwicki nov. 
See text figure 95 
Carapace semioval to semicircular; lateral and frontal margins form- 
ing a uniformly rounded curve; length to width as 2: 3; basal margin 
straight transverse. All margins apparently with a broad flat border. 
Lateral eyes large, about one fourth the length of the 
carapace, elliptical in outline, prominent, situated for- 
ward, in front of the middle transverse line, less than 
their length distant from the margin. Length of cara- 
: Fig. E rpt 
pace of type, 11.6 mm; width, 16.2 mm. chadwieki Pan 
olotype. X 1.5 
Eusarcus linguatus nov. 
See text figures 96, 97 
Carapace semioval, with a tonguelike process in front; length to 
width as 4:5. Lateral margins moderately convex; frontal margin 
produced into a squarish process with rounded anterior angles; one 
