PALAEONTOLOGY OF NEW-YORK. 
The seale-like sculpture is rarely or never seen upon the carapace of the Eury_ 
pterus , and though sometimes conspicuous on the dorsal surface, is usually best 
preserved on the lower side of the body joints. The margins of the swimming feet 
in their last joints, and sometimes other parts, are faintly or strongly serrate in 
different species. The joints of the caudal portion in the different species vary con- 
derably in the posterior marginal extension on each side, which is sometimes almost 
spiniform. 
With a single exception, all the specimens of these crustaceans, showing the feet, 
have the joints of these organs short and numerous : in that exception, these ap¬ 
pendages are more slender, and the joints much elongated, four or five only having 
been preserved, and these show no small spines at their tips. In the articulations, 
and in the proportions of the parts of the body, this specimen bears more resem¬ 
blance to the figure of Ptenjgolus above referred to; but in other respects it has the 
character of Eurypterus , preserving the maxillary plates of the posterior pair of 
feet, with serrated margins, and a narrow cordiform post-oral plate, while some 
portions of the last pair of feet still remain. The joints of the body do not differ 
from those of other species of Eurypterus , except in having a greater proportional 
length. 
The specimens heretofore known, both in Europe and America, have the lunate 
or reniform eyes placed much within the margin of the carapace; and this feature 
is regarded as of generic importance. In a single carapace, which has otherwise all 
the appearance of belonging to Eurypterus , the eyes are broadly oval, and placed 
on the margin of the carapace; but this may be a Pterygotus , or an allied genus. 
The figures on the next page, representing a restoration of the Eurypterus , are given 
from the examination of numerous specimens; and every part here represented has 
been seen in its proper place and in its true relations to other parts of the animal, 
as will be shown hereafter in the several parts of E. remipes and E. lacustris and 
others. 
The rows of dark spots on the back of the specimen fig. 1 indicate the scale-like 
elevations, of which, in very perfect specimens, we have four series on the first six 
segments, and two on the next six segments of the body. In the compressed speci¬ 
mens, and in impressions of the body in stone, these marks often appear like pores 
penetrating the crust; but I have not found evidence of any such feature in the 
more perfect specimens examined. 
