288 NEW YORK STATE MUSEUM 
Subgenus D. (Drepanopterus) 
S. lobatus Laurte | 9S. bembycoides Laurie . 
S. pentlandicus Laurte S. longicaudatus mov. 
Indeterminate species 
5S. megalops Salter | 9. beecheri Hall 
S. ensiformis H. Woodward oS. ? limbatus nov, 
Ss. symondsi (Salter) S. myops Clarke 
Among the American species only group B (Ctenopterus) and group 
D (Drepanopterus) have thus far been recognized, the former with one, 
the latter with two species. The subgeneric relations of the four other 
American species: S.excelsior, 58. beecheri, S.?limbatus 
andS. myops remain undetermined. 
Stylonurus (Ctenopterus) cestrotus Clarke 
Plate 49; plate 50, figures 1-7 
Kurypt e rus? cestrotus Clarke. N. Y. State Mus. Bul. 107. 1907. p. 307, 
pl. 3, fig. 8-10 
The original description of this species reads: ‘‘ Of this species we have 
only enough to satisfactorily establish its difference from other forms— 
the two specimens here illustrated. Both show the peculiarly ornamented 
frontal border of the cephalcn which carries a row of denticulations. One 
of these specimens conveys a satisfactory idea of the form of the body, 
and presents the ventral aspect but there is some uncertainty in regard 
to the number of segments and though evidences of four pairs of legs are | 
present the structure of these is not apparent. The head shown in figure 
to indicates that the compound eyes are large and very far forward. It 
is entirely probable that when this species becomes better known it will 
have to be excluded from the genus Eurypterus.”’ 
The larger collections acquired since this date and the development 
of the counterpart of the first of the two specimens figured in the prelim- 
inary paper, have afforded sufficient data to form a fairly accurate con- 
ception of this most peculiar type. 
Description. ody of small size, slender and terete, all parts being 
‘noticeably elongate. 
