122 BRITISH FOSSIL CRUSTACEA. 



Crustacea. During my last visit to Scotland, in August, 1871, the only additional 

 materials for my Monograph which I then obtained consisted of the specimens of 

 Eurypterus Scouleri from my friend Mr. Powrie's collection. 



The most important characters by which the genus Stylonurus is distinguished are 

 the peculiar form of the carapace, the great length of the telson or terminal joint (in 

 S. Powriei one third the length of the entire animal), and the substitution of two pairs of 

 long, slender, oar-like jaw-feet, instead of the single pair of broad, short, natatory organs 

 more usually met with in this group. 



Species 1.— STYLONURUS POWRIEI:— H. Woodw. PI. XXI, fig. 1 (and fig. 2?). 



Stylonurus, Page. British Assoc. Report, Glasgow, 1855, p. 89. 



— Powriensis, Page. Advanced Text-Book of Geology, 185G, p. 135, 



%• 2. 



— Powriei, Page. Op. cit., 2nd edit., 1859, p. 181, fig. 3. 



— — H. Woodw. Brit. Assoc. Report, Bath, 1864, p. 73. 



— — H. Woodw. Quart. Journ. Geol. Soc, 1865, vol. xxi, p. 482, 



pi. xii, fig. 1. 



Stylonurus Poioriei was obtained from the Old Red Sandstone of the Turin Hill range, 

 near Pitscandly, in Forfarshire, by Mr. James Powrie, F.G.S., of Reswallie, after whom 

 it has been named. 



The impression and counterpart of S. Powriei being only on sandstone, and, in all 

 probability, the interior side of the upper surface, do not afford such good material for 

 description as the specimens of the other species to be hereafter mentioned. 



Dimensions. — The Carapace measures 2 inches 3 lines across at its posterior border, 

 and 2 inches 7 lines in its greatest breadth, and 2 inches in length. It is bordered in 

 front by a deep groove, \t\\ of an inch from the external margin, which gradually unites 

 with it half-way up the sides, which rapidly contract for \t\\ of their length before reaching 

 the posterior angle. 



The Eyes are placed fths of an inch apart, on either side of a median furrow, which, 

 passing forward, divides into two semicircular arches, and is lost in a series of minute 

 tuberculations. On either side of the median line are two small oblong tubercles, placed 

 between and slightly in front of the eyes. The eyes themselves can hardly be said to be 

 preserved in this specimen, but their position is clearly indicated. 



Only two pairs of long appendages in 8. Powriei are known. The basal joints of 



