DROMILITES. 27 



diminish in size pretty regularly from the second to the fifth pairs, that they are generally 

 slender and smooth, and that the fifth pau' are tm-ned upwards over the back, as in 

 so many of the Anomiu'ous forms. 



Length of carapace 1"7 inch; breadth, 2 inches. 



Obs. It has been very difficult to assign to this species its relation to any of the known 

 families of Crastacea, nor is it even certain whether I am right in placing it amongst 

 the Anomura. I have been led to this opinion, however, by several points in its stmcture 

 which approximate to those found in many forms of that group ; particularly the large 

 open orbits and the small size and dorsal direction of the posterior pair of feet. This 

 latter chai-acter is imphed from the first joint only of the feet, the situation of which in the 

 two specimens hi which I have seen them, is imequivocal.* The remarkable structm-e of 

 the hand is, as far as I know, without any parallel in the whole class. The hand is so 

 produced on its lower side towards the anterior part, as to occupy the position and to bear 

 the function, also, of that process which is commonly called the immoveable finger, and it 

 is opposed the whole length of its anterior margin to the finger which is bent down so as 

 to meet it. The nearest approach to this structvu'e in a recent form with which I am 

 acquainted, is in the Itanina, in which, however, this abnormal condition is much less con- 

 siderable. There is also an approach to a similar structure in the Eocene Arcliceocarabus. 



There are numerous specimens both in Mr. Bowerbank's and Mr. Wetherell's 

 collection, as well as some fine ones in the British Museum, derived, I beheve, -wholly 

 from Sheppey. 



Order— ^iVOi¥KS^. 

 Sub-Order— APTERURA. 



i^a»n7y— DROMIAD^. 



Genus — Dromilites, Edioards. 



Char. Gen. Testa suborbicularis, postice latior, fronte incurvo ; regionibus distinctis, 

 brancliiaU maxima, in partes duas sulco et carina transverse divisa, quarum posterior 

 rugosa, ad mediam testam fere extendens. Pedipalpi externi oris apertm-am implentes, 

 caule exteriore subulato, piano ; cauhs interioris articulo sccundo paulo longiore quam 

 latiore^ tertio a;que quadrato. Pedes antici equales, testa longiores, digito immobili 

 apicem versus digitato ; 2^edes quartus et quintus reliquis minores, supra dorsum reversi. 

 Abdomen in utroque sexu segmentis omnibus separatis, segmento sexto apud angulum 

 antico-exteriorem appendice instructo. 



* See figs. -1, 5. 



