THE EURYPTERIDA OF NEW YORK 279 
retained the last long leg and several of the anterior limbs scattered 
about the carapace, furnished the evidence for the two pairs of short 
limbs in his restoration. Woodward figured in front of these two feeler- 
like appendages which in Beecher’s restoration of 5. excelsior are 
replaced by a first pair of short walking legs, the latter together with a 
chelicera having been successfully prepared by Clarke [1888, pl. 26A)]. 
An example from the dark shales at Otisville has shown by prepara- 
tion a series of four legs on one side and this species exhibits in the forma- 
tion of its carapace the typical characters of a Stylonurus. The structure 
of this species, S. cestrotus, has suggested a different conception 
of the limbs of Stylonurus, for, (1) the last two legs are of distinctly 
different length, (2) the second and third pairs of legs are so long as to form 
a progressively growing series with the fourth and fifth pairs. The 
question then arises whether Stylonurus had been incorrectly understood 
or whether the Otisville form represents a new and different group. 
A survey of the 13 species, cited below as falling under the head of 
Stylonurus by virtue of the characters of their carapaces and abdomina, 
shows that, besides the original representatives of the genus, 5. powriel 
and logani, of only four species are specimens known that retain suf- 
ficient fragments of the legs to indicate their structure. These are 8. 
macrophthalmus and S. elegans Laurie, 5. cestrotus 
Clarke and S. scoticus Woodward. Taken together these demon- 
strate two important facts; (1) that the legs increased in. length quite 
regularly backward instead of being divided sharply into two different 
sets as represented by Woodward and Beecher: an anterior one of very 
short legs and a posterior one of exceedingly long ones, (2) that there are 
three distinct types of legs among species referred to this genus. 
As already stated, Woodward seems to have combined the aspects 
of his specimens of S. powriei and S. logani to effect his 
restoration of S.logani; the former furnishing the two long legs, the 
other the preceding two short pairs. In considering the question of the 
two ‘‘subequal” long pairs of swimming legs, it may be observed that the 
