• PALJIONTOLOGY OF NEW-YORK. 



The scale-like sculpture is rarely or never seen upon the carapace of the Eury_ 

 pterusy 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 sn;all 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 Pterygolus 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. 



