278 NEW YORK STATE MUSEUM 
shown by Stylonurus symondsi (Salter) [see Woodward, 1872, 
pl. 21, fig. 4] and S. macrophthalmus Laurie. Neither of 
these two species, however, has as long a carapace as D. stylo- 
nuroides. D. macrochirus has a shorter carapace and is a much . 
larger species. 
Genus STYLONURUS Page 
The genus Stylonurus was proposed by Page in 1855 in a paper read 
before the British Association [see Bibliography]. It was based on a single 
species (S. powriei) figured and named the following year in his 
Advanced Text-Book of Geology. Only a single specimen, not very favorably 
preserved in sandstone, has been recorded and although Page’s not very 
correct figure and explanation have been followed by Woodward's 
elaborate description and careful illustration, this genotype is still incom- 
pletely known. Indeed, when the investigation of a considerable number 
of species revealed to us the presence of divisions of undoubted subgeneric 
rank, it remained doubtful with which of these the genotype belongs and 
which of the divisions therefore represents Stylonurus sensu stricto. A con- 
ventional conception of the genus has been created by the. restorations 
made by Woodward and by Beecher. ‘ Woodward’s restoration is based. 
on the species S. lo gani, and Beecher in his restoration of 5. excel- 
sior had to follow Woodward in nearly all important features, only 
the carapace, the chelicerae and first pair of legs of 5. excelsior 
being known. | 
It is especially on the character of the limbs that the most important 
subgeneric differences are to be based; it is therefore necessary to subject 
the genotype and the restorations mentioned to a critical review in regard 
to these structures. Woodward’s conception of the relative lengths of 
the legs obviously resulted from a combination of the two specimens of 
S.powriei and S. logani. The former furnished the evidence 
for the conclusion that the last pairs of legs are 
length and breadth’ [1872, p. 123], for 1t was the only specimen known 
to him retaining these legs; while the specimen of 5S. logani which 
‘ 
‘about equal both in 
