STYLONURUS SYMONDSII. 125 



of Eurypterus Symondsii, was obtained from the middle beds of the Old Red Sandstone 

 (" Cornstones") of Rowlestone, south of the Hay, Brecknockshire. Only the carapace 

 has as yet been obtained, but its square form, and the indications of the bases of the 

 great sub-central eyes, leave me in no doubt in referring it to Stylonurus. 



It was named Symondsii in honour of the Rev. W. S. Symonds, E.G.S., of Pendock 

 Rectory, near Tewkesbury, by whom it was first brought under Mr. Salter's notice, and 

 lay whose interest the original specimen is now preserved in the Museum of Practical 

 Geology, Jermyn Street. A cast of the same may also be seen in the British Museum. 



The specimen, of which we have only the exterior cast of a head, perfectly repre- 

 senting the surface, however, is impressed on a slab of brownish-gray micaceous grit, 

 from the Upper Cornstones of Rowlestone, Brecknockshire, and was obtained by the Rev. 

 Mr. Wenman. It is 2^ inches long, and 2^% inches broad at the wide anterior part^ 

 the greatest breadth being at the anterior third ; the hinder edge is only 2 inches wide. 

 The front margin is arched, and somewhat truncate in front, and gibbous at the sides, 

 and from about halfway up the head it is double, or has an inner raised ridge 2 lines 

 distant from the edge. This ridge is continuous all round with the somewhat elevated 

 border of the sides, in such a way that the carapace appears complete, without the 

 addition of the anterior border. 



Exclusive of this border, which is concave, and somewhat bent downwards, the 

 surface of the head is but very gently convex, and is covered, except along the posterior 

 margin, by elevations and furrows, which give it a very rugged and lobed aspect. A 

 deep Y-shaped vertical furrow, forked upwards at an angle of 30°, divides the space 

 between the eyes, and occupies the middle third of the head ; l the space between the 

 branches is very convex. 



A shallower depression takes its origin above the eyes, and radiates outward to the 

 front margin ; a pair of shorter furrows run obliquely outwards behind those organs ; 

 another deep oblique depression occurs further back, at half an inch from the hinder 

 border, and outside it a strong triangular lobe is marked out, partly by this furrow and 

 partly by a submarginal one, which occupies about one third the length of the head. 

 Between these strong lateral lobes, and on the same level, a central tubercle, flanked by 

 two depressions, occurs immediately behind the deep Y-shaped furrow first noticed. 

 Lastly, there is a short and shallow pair of furrows in the central front portion of the 

 head. 



The posterior border is quite plain for a breadth of half an inch, and free from ridges 

 or furrows of any kind. The posterior angles are slightly obtuse and not at all produced, 

 the hinder edge is sinuous, and without the raised border which runs round all the rest of 

 the margin. The eyes are large, rounded, and circumscribed by a sunken space ; they 

 •are placed more than half-way up the head, and as wide apart as they are distant from the 



1 In E. Scouleri there is a ridge, forked downwards, between the eyes. 



