﻿142 



BRITISH FOSSIL CRUSTACEA. 



however, been met with in Pterygoids (page 60), and in Slimonia (p. 112). There 

 are at least eight articulations in the antennules, but I cannot positively discern a 

 ninth. 



The lateral lobes of the thoracic plate in the individual of this species originally 

 described by us and figured on PL XXVIII, fig. 2, and 2 a are much deeper, in propor- 

 tion to the pair of median appendages, and the two intercalated plates are larger than in 

 the American Enrypteri. 



Fie. 44 



Fig-. 44. — Diagram-figure of Eurypterus lanceolatus, Salter, restored chiefly from 

 fiar. 2, PI. XXVIII. The endognaths are given upon the authority of Mr. 

 Robert Sliraon, of Lesmahagow, Lanarkshire. 



1. The dorsal a?peet of the body. 2. The ventral aspect of the body — a, the 

 antenna? ; b, e, d, the endognaths ; e, the ectognaths ; t, t, the thoracic plate, 

 or operculum. 3. One of the antennae enlarged, from a detached example 

 found by Mr. Slimon. 



1—12, body-segments; 13, telson. (See ' Geol. Mag.,' 1864, vol. i, p. 107, pi. v, 

 figs. 7, 8, 9.) 



In fig. 1, PL XXVIII, however, there is evidence of a much longer median 

 appendage, seen as an impression lying beneath the 9th, 10th, and 11th segments, and 

 probably not less than 8 lines in length. It is highly probable, as stated elsewhere (see 

 ante, pp. 114 — 118), that this variation in the form of the central appendage is a sexual, 

 and not a specific, character. 



