40 POSSIL MALACOSTRACOUS CRUSTACEA. 



process. Abdomen somewhat compressed, evenly rounded on the back part, and without 

 any carina or other inequality of the surface ; the segments polished and everywhere 

 punctate, cxcepting-that portion of each which slides under the margin of the one before it, 

 which part is more highly polished, and almost wholly without puncta ; the first segment 

 is the narrowest, the second has the lateral or epinieral piece broad, nearly quadrate, 

 with a sharp, triangular, hooked process'' at the posterior angle ; the epimera of the 

 third, fourth, and fifth segments are triangular, falcate, the inferior angle directed 

 backwards, the sixth is very broad, and deeply notched for the attachment of the 

 base of the appendages, forming the external portions of the tail ; the seventh segment 

 or central portion of the tail is semi-elliptical, evenly rounded at the posterior margin, 

 with two slight ridges diverging forwards ; the outer member of the tail curved, and 

 divided transversely at about one thu'd from tlie extremity, and with a slight longitudinal 

 ridge ; the inner member as broad as it is long, rounded, the posterior margin truncate, 

 with a longitudinal ridge ; anterior pair of legs unequal ; both much more slender 

 and less robust than in //. gammaroidcs. The arm is long, triquetrous, enlarging 

 forwards, the wrist also elongate, with two or three tubercles near the anterior margin ; 

 the hand of the larger claw with a few triangular teeth on the inferior margin, 

 the upper face with an even and obtuse ridge, extending its whole length, and 

 continued along the immoveable finger to its extremity ; the fingers of the larger 

 claw are furnished with several strong tubercles, and numerous smaller ones; the 

 smaller hand resembles the other in its general characters, but it is nmch more 

 slender, less curved at the margins, and the fingers are armed only with numerous 

 minute, nearly equal denticidi, without any larger tubercles ; the remaining legs appear, 

 froiiJ the fragments which have been observed, to be very slender, quite smooth, and 

 polished. 



Obs. In its proportions, the species appears to resemble II. longimana (Sp. Sowerby)> 

 of the Lower Grecnsand, before alluded to, much more nearly than its neighbour of 

 the London Clay, //. (jammaroidcs, which is, in all its proportions, more I'obust and solid 

 than cither of the others. 



The polished sm'face of the abdomen, the regularly granulated carapace, and 

 the general elegance of its form, render this species one of the most beautiful of 

 the known fossil Crustacea. It is more frequently found in the northern 

 suburbs of London, where it is very numerous, than in other localities, although 

 there arc several specimens both in Mr. Bowerbank's and ]Mr. Wetherell's 

 collections from Sheppey. It is observable that the specimens olitained from the 

 former locality are, almost universally, cleaner and more polished than those from 

 the latter. 



There is a specimen in j\Ir. Wetherell's collection, of which I give a figure in 

 Plate X, fig. 9, which differs in some respects from the normal character of //. Belli, 



