THE EURYPTERIDA OF NEW YORK 205 
rounded and in many the disk is distinctly heart-shaped. About the center 
are two darker spots which represent a pairof pitlike depressions. The scales 
are largest and most crowded on the anterior half of the segment. The over- 
lapped anterior fifth of the segment is sharply set off from the remainder 
by a line of oval disklike scars and the overlapped part itself is densely 
crowded with smaller scales which in front consist of crescents and behind 
change gradually into the disks, thereby evincing the morphologic and 
functional identity of these peculiar disklike scales with the crescentic scale 
of other eurypterids. 
A brief study of the ornamentation of Pohlman’stype of E. gigan- 
teus (=E. pustulosus Hall) figured on the same plate as his 
Pterygotus globicaudatus, shows it to be of quite the same 
character and relative dimensions as the latter, the fact being taken into 
account that the sculpture pustules of the eurypterids are always of smaller 
size and at the same time more prominent on the carapace than on the 
body. The enlargements of the ornamentation of the typeof E. gigan- 
teus [pl. 24, fig. 2, 3] show that the carapace was covered with large 
wartlike pustules in front of the eyes, which are flat on top or slightly 
sunken in. They are now filled with rock and were hence originally hollow 
and probably rounded on top. Between them are found many smaller 
ones, scalehke, with thicker test, which exhibit the disk shape of those of 
P. globicaudatus, asseen on the anterior portions of the segments 
[pl. 24, fig. 4]. Like scales are observed on the first tergite of the type of. 
E. giganteus and since the sculpturing as a rule increases in coarse- 
ness from the first tergites posteriorly, there is no doubt that this 
ornamentation fully corresponds to that seen on the postabdomen of 
P. globicaudatus. 
It is hence, manifest that P. globicaudatus and E. gigan- 
teus are of the same species and as E. giganteus is identical with 
E. pustulosus the original P. globicaudatus represents 
the postabdomen of E. pustulosus. The species characters are 
then the following: 
