THE EURYPTERIDA OF NEW YORK 287 
term Ctenopterus may be applied to this group. The leg from the Utica 
shale figured by Walcott as Echinognathus clevelandi, 
shows a like structure in exaggerated form and may prove to represent 
the group, in which case the term Echinognathus would take precedence. 
At present the employment of the latter term would be unwarranted as the 
body of the Utica form may be entirely different from that of Stylonurus. 
Subgenus C. This is represented alone by S. scoticus. Its 
differential characters are the flat broad last pair of legs, the greatly en- 
larged winglike epimera of the postabdomen and the emphasized sculpture 
of the posterior margin of the tergites. The short club-shaped telson 1s 
also notable. The carapace and the form of the abdomen are as in 
Stylonurus. We propose for this group the term Tarsopterus. 
Subgenus D. Finally Drepanopterus is, in our opinion, not more differ- 
entiated from the typical Stylonurus than S. scoticus, though it 
stands quite at the other end of the phylogenetic line. Drepanop- 
terus longicaudatus nov. is a form distinctly intermediate be- 
tween Stylonurus and the type of Drepanopterus. On account of its 
phylogenetic importance in the development of Stylonurus we have treated 
this division as a separate genus. | 
The majority of the species can not at present be definitely referred 
to any of these groups as only their carapaces are known. The following 
is a provisional synoptic table of the species: 
subgenus A. (Stylonurus s. st.) 
S. logani H. Woodward S. powriei Page 
S. macrophthalmus Laurie Stylonurus (?) scabrosus (H. Wood- 
S. ornatus Laurie ward) 
Subgenus B. (Ctenopterus) 
S. cestrotus Clarke ©. multispinosus nov. 
S. elegans (Laurie) (?) S. excelsior Hall, 
subgenus C. (Tarsopterus) 
©. scoticus H. Woodward 
