Page:Quarterly Journal of the Geological Society of London, vol. 27.djvu/396

 from any species previously examined by me, and of which I beg to subjoin a short notice.

The most perfect specimen, from which the restored outline (fig. 1) is taken, measures 2-3/4 inches in length, and 10 lines in its widest thoracic segment. All the somites are united ; and one of the swimming-feet, although injured, is still in place. The head, which is semicircular in outline, measures 4 lines in length by 9 lines in breadth ; the eyes are subcentral, and the ocelli nearly central, as in the other species of Eurypterus. The first six segments (thoracic) succeeding the head measure together 9 lines in length ; commencing with a breadth of 9 lines, they increase at the third segment to 10 lines, and diminish at the sixth segment to 7 lines in breadth. The segments increase in length and diminish in breadth very evenly from the third segment backwards. The borders of all the anterior segments are curved, and the posterior angles slightly produced and acutely pointed.

The six posterior (abdominal) segments diminish in breadth backwards from 6 lines to 2 lines, and increase, in the same direction, in length, from 1-1/2 line to 2-1/2 or nearly 3 lines, the body being terminated by a slender ensiform telson, or tail-spine, 7 lines in length. No sculpture is apparent on the segments or head; but the integument composing the former indicates its tenuity by abundance of plicae and wrinkles. The thoracic plate (fig. 3) is very characteristic, differing in the form of its median appendage from that of any previously described species. It is 9 lines broad, and 2-1/2 in depth ; the median appendage is spindle-shaped in outline, and is 3-1/2 lines in length and 1-1/2 line broad. The swimming-foot is 21 lines in width, and 3/4 of an inch in length, exclusive of the basal joint. The species agrees closely, in the form of its swimming -feet, with the American and Russian Eurypteri, having the same intercalated plate between the ultimate and penultimate joints, and also the minute terminal palette at the end of the seventh segment.

Numerous detached endognathary palpi occur associated with this

Fig. 1. Eurypterus Brodiei, H. Woodw. (outline restored, natural size). Passage-beds from the Uppermost Silurian to the Old Red Sandstone, Perton, near Stoke Edith, Herefordshire. Fig. 2. Palpus (enlarged). Fig. 3. Thoracic plate (enlarged).