THE EURYPTERIDA OF NEW YORK 295 
palpebral lobes is supported by the fact that in the National Museum 
Specimen this part projects prominently; further in all other species 
of Stylonurus the visual surface is a more or less narrow crescent on 
a circular base [seeS.megalops, 8S. myopsandS. scoticus ], 
and it therefore should not be assumed to be circular in S. excelsior. 
some closer study of the eye region in the two carapaces of S. ex- 
celsior has furnished the solution of these apparently contradictory 
facts in the finding of distinct, narrow crescentic, visual areas on the outside 
of the broken, circular, palpebral area. They are particularly well seen in 
the Rutgers College specimen, where they are clearly outlined although 
somewhat obscured by having become infolded at the collapse of the vis- 
ual node. | 
We picture, then, the original aspect of the eye of Stylonurus 
excelsior asa bulging subhemispheric, visual node, supported on the 
outside by the strong orbital ridge, on the inside by the median ridge of 
the carapace and the transverse palpebral lobes. At the apex of this 
node and at the outer end of the palpebral lobe the relatively small cres- 
centic visual surface was situated. 
It is obvious that the visual area did not keep step with the growth 
of the carapace and of the visual node and thus became finally a relatively 
small band around the apex of a high node. This giant merostome would 
thus seem to have possessed very small eyes in comparison with smaller 
eurypterids, a feature common in the giants of other groups, as in the 
whales and elephants among the mammals. 
Stylonurus? limbatus nov. 
Plate 85, figures 1-3,5 
The collections from Schenectady and Duanesburg contain half a 
aozen specimens that are strikingly different from the associated euryp- 
terids in greater relative length of carapace, broad, flat margin and sub- 
central position of the rather close-set large circular eyes, or eye nodes. 
All these characteristics suggest the generic reference of this interesting 
