strikingly long last two pairs, different groups have developed differently in regard to the preceding legs. In some these have remained relatively short and shaped as in Dolichopterus, in others they have grown in correspondence with the last pairs, are highly spiniferous, the spines becoming very long and increasing greatly in number [pl. 49, fig. 6] and in others again the spines of the first three pairs show a tendency to become flat and broad.
In Woodward's well known restoration of Stylonurus the animal is given three short pairs of anterior legs and two very long, subequal pairs of posterior legs, the latter being regarded as for swimming, and the former for walking. Laurie, who recognized the probable derivation of Stylonurus from Eurypterus through Drepanopterus, considered the sixth pair as being reduced "from the typical digging foot to a purely crawling one," adding: "This may indicate more purely littoral habits, or a more active predatory existence, demanding rapid locomotion rather than firm anchorage." Beecher's life size restoration of S. excelsior accepted Woodward's conception of the posterior legs, adding only the bladelike appendages of the short first three pairs of legs observed by Hall and Clarke in the first and second endognathites of S. excelsior and suggested that these legs "served partly as swimming organs."
From the somewhat diffeient restoration of Stylonurus, at which we have arrived in this paper and which is fully set forth in another place we infer that the animal was comparable to the existing gigantic Japanese spider crab, which some of its species rivaled in size. Like that grotesque creature it probably used its long hind legs to shove itself forward over the muddy bottom, while its short front legs indicate that the head lay near the bottom, the front legs being used for walking and grasping, and perhaps also, where the spines are broadened, as swimming organs. The extremely long styliform telson frequently with a blunt extremity, may have served less as a protecting than as a supporting organ of the long abdomen, and have aided in righting the awkward creature when it was overturned.
