314 NEW YORK STATE MUSEUM 
fragment of a segment [pl. 53, fig. 13] exhibits a curiously serrated pos- 
terior margin. This recalls the frontal serrations of the carapace of 
S. cestrotus, but the segments of that species have not shown this 
structure, although on account of their rather poor preservation, this does 
not yet demonstrate the absence of this fringe. We are not certain that 
this specimen is referable to Stvlonurus. 
To a gigantic Stylonurus or Pterygotus probably should also be re- 
ferred two fragments of plates with marginal rows of slightly curved, 
rather blunt spines [pl. 53, fig. 16, 17]. These are apparently portions of 
the manducatory edges of coxal segments. In the smaller specimen the 
teeth are very thick and solid, in the second they are so much wrinkled 
and shrunken that they give the impression of having been hollow pro- 
cesses. It is possible that these remains require an entirely different 
explanation, but the material is at present too fragmentary to permit of 
positive conclusions. There is a suggestion of similarity between these 
peculiar fringed bodies and the supposed combs of giant scorpions such as 
have been described by Peach as Glyptoscorpius, both the fringe and 
the parallel lines of the base of the fragments indicating the structure 
seen in the rhachis and the comb of certain recent scorpions. With present 
knowledge the comparison can be carried no further. 
| Subgenus DREPANOPTERUS Laurie 
In 1892 Laurie created a new genus for a single, then rather incom- 
pletely known eurypterid, from the Siluric rocks of the Pentland hills in 
Scotland. He defines the genus as follows: 
Carapace broader than long; widest about two fifths from anterior 
margin. Body, 1st segment wider than posterior margin of carapace; 
increases in width to 3d segment, and-then tapers rapidly. Limb elongated, 
subcylindrical, terminating in a very slightly expanded joint, concave on 
posterior margin. 
The subsequent discovery of two other species and of better speci- 
mens of the genotype led Laurie [1899, p. 582] to consider the point of 
_ chief generic importance to be a negative one: ‘‘ Last pair of appendages 
