176 BRITISH PALAZOZOIC FOSSILS. [Crustacea. 
The semicircular scale-like ridges of the carapace are rather irregular in size, but the larger entirely 
covered by the smaller, otherwise resembling the fragment in Sir R. Murchison’s Sil. Syst. from the Upper 
Ludlow, and named Pterygotus problematicus by Agassiz. The pincers are very remarkable; instead of being 
excessively thick and strong and armed on the inner edges with powerful teeth, as in the Pterygotus Anglicus, 
they are perfectly unarmed, and so long and slender as possibly to indicate a separate genus, which might 
be named Leptocheles (derris, tenuis, and yn}, forceps). It strikes me forcibly (judging from the figures) that 
the Onchus Murchisoni (Ag.), figured in the same work and from the same bed as the P. problematicus, 
is not an Ichthyodorulite, but the long fingers of the chelz of this crustacean, the size, form, and sculpturing, 
agreeing very nearly. In the same bed as the long chele and fragments of carapace here described, were 
found one moveable finger, and one perfect claw with both fingers im sitw of a much shorter form, the hand 
about three lines wide, the penultimate immoveable finger about one inch long and rapidly tapering from 
two and half lines wide at the base to the tip; it is longitudinally sutcated like the one above described: 
the last joint or moveable finger is very different, being perfectly flat, triangular, seven lines long, one and 
half lines wide at base, and tapering rapidly to a point, the inner edge being straight and simple, the outer 
edge slightly convex. The hands of both kinds of chel are similarly sculptured with fine sharp, short, 
irregular, longitudinal, curved plice, It seems probable therefore that more than one pair of feet were 
didactyle. 
Position and Locality—In the fine olive-schists, Leintwardine. 
Explanation of Figures.—P\. 1. E. fig. 7. The long penultimate or immoyeable Onchus-like finger of 
one of the didactyle pincers, with a portion of the peculiarly sculptured crustaceous hand connected with 
its base, natural size; from Leintwardine—Fig. 7a. The terminal or moyeable finger of probably the 
same pincer, seen from the opposite side, also shewing trace of the peculiar sculpturing of the hand near its 
expanded articular base; same locality—Fig. 76. Portion of the sculpturing of the hand of fig. 7 mag- 
nified three diameters.—Fig. 7c. A shorter didactyle claw, or pincer, with both fingers im situ belonging 
to a different pair from fig. 7, having a portion of the crustaceous hand and carpus attached, with traces 
of sculpturing resembling that of fig. 7 in character; same locality—Fig. 7d. A detached terminal joint 
(or the moveable finger) of a pincer identical with that of 7¢; same locality. 
