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. stylonuroides. 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 incompletely 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 conventional 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. logani, and Beecher in his restoration of S. excelsior had to follow Woodward in nearly all important features, only the carapace, the chelicerae and first pair of legs of S. 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 "about equal both in length and breadth" [1872, p. 123], for it was the only specimen known to him retaining these legs; while the specimen of S. logani which
