MARINE CRUSTACEANS. 



XIII. THE HIPPIDEA., THALASSINIDEA AND SCYLLARTDEA. 



By L. a. Borradaile, M.A., Lecturer in Natural Sciences 

 at Selivyn College, Cambridge. 



(With Plate LVIII.) 



Fourteen species belonging to various groups of reptant decapods are enumerated in the 



following lists. Two of them are new. All the rest have already been recorded from the 



Indopacific region, with the exception of a species of Callianassa which I am unable to dis- 

 tinguish from a Martinique form. 



Suborder Anomura. Tribe Hippidea. 



The members of this gi-oup are all shallow water forms which live buried in the sand. 

 They are particularly plentiful at the very edge of the water on beaches of loose sand, 

 retreating with the outgoing tide and burrowing with extraordinary rapidity by means of their 

 flat legs with sickle-shaped ends. Garstang has described' the way in which the antennules 

 of Albunea are adapted to this habitat, forming a filter to keep the sand out of the breathing 

 stream. In the case of most species of Remipes a sort of chamber is formed by the long 

 hairs on the short antennae and inner flagella of the antennules-. The animal lies in the 

 sand with the eyes just showing and this chamber at the surface to filter the water. It may 

 easily be caught b}' a bait of crab at the end of a line, pouncing on it with its sharp 

 maxillipeds and allowing itself to be flicked out of the sand if the rod be shaiply lifted. 



Quite a number of the peculiarities of other sand Decapoda are repeated independently 

 in the Hippidea. The so-called subchelate hands of Albunea are found, as we have seen 

 (p. 683), in various Oxystomes and Parthenopidae and in Kramsia, and the flattened legs of 

 all Hippidea in Ranina, Matuta and Kraussia. The overlapping carapace of Remipes is also 

 common among Oxystomes and Parthenopidae. The outward channel from the gill-chamber is 

 can-ied, in Hippidea as in Oxj^storaata, by the endopodite of the first maxilliped. The anten- 

 nules of Albunea are analogous to the antennae of the Corystidae. And the smooth surface 



' Q.J. U.S. XL. p. 221. I regret the accidental omission Mr Garstang were confirmed, 

 of a reference to this paper from tlie article on the Oxysto- - This is not conspicuous in the species figured below, 



mata, in the course of which some interesting suggestions of 



