new species of British Crustacea. 319 



This crustacean^ unlike the Talitra, Gammarus, and other allied 

 genera, is remarkably sluggish in its habits, and lives almost 

 wholly beneath the sand, into which it buiTows, and from which 

 it appears only to come out just after the receding of the tide, 

 when it gropes to a distance of about a foot, and again burrows 

 beneath its surface. The legs, which by their formation are all 

 lessened in their capability as members of perambulation, obtain, 

 through the great expanse of surface which each joint displays, a 

 paddle-like power, by which they are enabled to progress through 

 the sand without resorting to leaps and bounds, the usual mode 

 of passage among the Talitra, or by crawling whilst lying upon 

 the side after the manner of Gammarus and other Amphipoda. 



I believe the manner in which the respiratory process is car- 

 ried on in this order of Crustacea is supposed to be by a current 

 excited through the agency of the natatory feet, passing con- 

 tinually over the branchiae situated beneath the thorax ; but the 

 peculiar habits of this animal, living as it does chiefly beneath the 

 sand, must materially interfere with the passage of such a current. 

 Then may we not presume, that the great extent of dermal sur- 

 face, which is prolonged by large hair-like processes, may offer 

 a medium through which the blood may be aerated, and so lessen 

 the dependence of vital action upon the waters circulating freely 

 over the branchial organ ? This seems to be supported by the 

 fact, that blood-discs pass into the hair-like processes on the 

 surface of the flabellse in the Brachyura. 



The eye is covered by the first ring, and is not distinguishable 

 above except by the assistance of transmitted light. 



The colour of the animal is of a pale muddy gray. 



It lives in sandy bays between the tides. I have taken them in 

 company with Messrs. Jeffreys and Moggridge, both in Oxwich 

 and Rhosilly bays near Swansea. 



I have named the genus Bellia, in order as much as possible 

 to identify Prof. Bell with the Crustacea, a class of animals to 

 which he has given particular attention. 



EXPLANATION OF PLATE XL 



Fig. 1. First pair of legs. Fig. 5. Fifth pair of legs. 



— 2. Second ditto. — 6. Sixth ditto. 



— 3. Third ditto. — 7- Natatory feet. 



— 4. Fourth ditto. — 8. Bellia arenaria, 



Amphitoe Moggridgei. PI. X. fig. 10. 



Back carinated, the three last rings of the thorax gradually 

 increasing in length at the centre of the posterior margin into 

 the form of a sharp tooth, which arrives at the greatest develop- 

 ment in the two first rings of the abdomen, upon the centre of 



