SULCATOR. 
175 
in their capability as members of perambulation, obtain, 
through the great expanse of surface which each joint dis- 
plays, 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 Talitri, or by 
crawling whilst lying upon the side, after the manner of 
Gammarus and other Amp/tipoda. 
Sulcator marinus, Spence Bate. — Basis of three hind 
legs not developed in the form of scales. 
Banff (Mr. Edwards) ; Macduff (Mr. Gregor). 
Mr. Spence Bate, in writing on the habits of Sulcator 
arenarius* remarks that naturalists suppose the respiratory 
process to be carried on in Amphipoda “ by a current ex- 
cited 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 surface, 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 
* Ann. and Mag., 2nd series, vol. vii. p. 319. 
