1 12 NEW YORK STATE MUSEUM ' 



the carapace distant from the frontal point. The ocelli are placed 

 on a line connecting the posterior edges of the lateral eyes. The 

 swimming legs are short, about as long as the base of the carapace. 

 It is especially the "paddle" that is relatively shorter and stouter 

 than in other species of Eusarcus, while the " arm " is relatively 

 longer and less compact; in other words, the swimming feet of this 

 species approach those of Eurypterus. The dorsal plates of the 

 abdomen are broken away and only the interior of the ventral side 

 is shown with a trace of the operculate appendage. The abdomen 

 does not seem to have widened abruptly as in the E . scor- 

 p i o n i s , but, if at all, more gradually as in E. cicerops. 



Measurements. The carapace is 16 mm long by 22 mm wide. It 

 is probable from some folds in the test that the carapace is some- 

 what contracted in antero-posterior direction and was a little less 

 broad. The lateral eyes are about 3 mm long. The abdomen is 

 but 22 mm wide, but clearly not fully preserved. 



Remarks. It is a remarkable fact that in distinction from the 

 Buffalo pool and the Shawangunk grit at Otisville, the Herkimer 

 pool has in all the large collections obtained there, afforded but this 

 one specimen of Eusarcus. And it is further noteworthy that this 

 species is more closely related to the E. cicerops from the 

 Shawangunk beds than to the E. scorpionis from the Bertie 

 waterlime. It differs from the latter in the broader outline of the 

 carapace, the position of the lateral eyes farther back along the 

 lateral margin and the position of the ocelli between the lateral 

 eyes as in E . cicerops, while in E. scorpionis they 

 lie in the middle of the carapace. In the former species' we have 

 lately observed that even in the type specimen (see N. Y. State Mus. 

 Mem. 14, pi. 36, fig. 4) there is the snoutlike lobe much more pro- 

 duced than we have figured. It is very much like that of E . 

 v a n i n g e n i . With the latter species, E. trigonus has the 

 position of the ocelli in common, but differs in the position of the 

 lateral eyes, which in E . v a n i n g e n i lie far within the margin. 



The possibility that the specimen could be a Eurypterus 

 r e m i p e s preserved in an incomplete and deceptive fashion is 

 excluded by the facts that, on one hand, the lateral eyes lie much 

 farther forward than they are found in a carapace of that species 

 with the basal width of our specimen ; and, on the other, the ocelli 

 are situated behind the lateral eyes while in E. remipes they 

 are found between them. 



