296 NEW YORK STATE MUSEUM 
species to Stylonurus. The presence of this genus, or rather of that branch 
of the eurypterids which leads to the late Siluric and Devonic Stylonurus, 
is further indicated by body segments (tergites) [pl. 85, fig. 6] which have 
the form and ornamentation of the Otisville species Stylonurus 
myops. 
Description. Carapace elongate semielliptic, a little longer than wide, 
widest at the base and contracting uniformly to the front which is evenly 
rounded. The posterior margin is straight transverse. The carapace is 
surrounded on all sides by a distinct border which is broadest in front 
where it attains one eighth the length of the carapace, and narrowest 
along the posterior margin. On the upperside this border slopes outward 
and is smooth, on the underside it was flat and concentrically grooved. 
The eye nodes are large, about one fifth the length of the body, circular, 
situated just in front of the transverse middle line of the carapace, close-set, 
about their own diameter apart. The visual surface has not been clearly 
distinguished from the node and it may have occupied the entire node. 
The ocelli have not been seen. The ornamentation is not visible on the 
carapace, but tergites probably belonging to the same species show circular 
to elliptic, relatively large nodes. 
The tergites are strongly curved, convex forward in the middle and 
at the antelateral 
’ 
concave toward the sides, with very prominent “ ears ’ 
_ angles and much rounded postlateral angles. They were very convex in 
the middle and surrounded by a depressed border. 
Long slender tubular leg segments [pl. 85, fig. 9] and broad flat leg 
spines also occur in the Frankfort shale, such as among the later euryp- 
terids are only known from the Stylonurus group. 
Horizon and localities. Frankfort shale (Schenectady facies) at Sche- 
nectady and Duanesburg. 
Remarks. Besides these elongate carapaces, a broad short carapace 
with the eyes far apart has been found at Schenectady [pl. 85, fig. 4]. This 
closely resembles the S. myops from Otisville. Like the latter, it 
has a very broad, concentrically striated or grooved border. ‘This cara- 
