1899.] A. Alcock — Neiv and Rare Species of Crustacea. 113 



But even here, though the association seems to have become mnch 

 more intimate and permanent, there seems to be no essential adaptation 

 of either animal to the other, nor does it appear to be beyond tlie 

 bounds of possibility that each might exist— though its existence might 

 not be so complete and secure — apart from the other. 



In the case of the new form of Hermit-crab, now to be described, 

 there is no evidence of the intervention of a shell, or other adventi- 

 tious support, at any stage. Captain Anderson dredged 205 specimens, 

 of both sexes and all ages, and in every observable instance the parent 

 polyp of the protective colony appears to have settled on the hinder 

 end of the abdomen of the crab and to have gradually spread by bud- 

 ding as the latter increased in size ; so that the intimate and immediate 

 connexion between the two animals appears to be, from the first, a 

 necessary one. 



In other words, the peculiar interest of the case is that the two 

 animals seem to have become directly adapted to one another, and to be 

 incapable of a separate and independent existence. 



For the Hermit-crab I propose the generic name Ghlsenopagurus^ 

 from ;>(Xaiva a large square mantle worn over the chiton, in Homeric 

 times, as a defence against the weather. According to Liddell and 

 Scott the chlaena was of a purple colour, which also corresponds with 

 the colour of the polyps that form the Hermit-crab's mantle. 



For the polyps I am not at present in a position to propose a name. 

 They belong to the family Zoanthidse, but not, as far as I can make out, 

 to any known genus. The colony consists of a copious lamellar coeno- 

 sarc in which the polyps, which are small and have not very numerous 

 tentacles, are deeply embedded : the coenosarc is perfectly soft, fleshy, 

 and flexible, without any incrustation or deposit. 



Chlaenopagurus, gen. nov. 



Carapace membranous, except in the cardiac region and the region 

 enclosed by the cervical groove, which are perfectly calcified. Rostrum 

 prominent. 



Abdomen a soft membranous obscurely-segmented bag ; symmetri- 

 cal in the male, although the appendages of the 3rd, 4tli and 6th somites 

 are developed on one side only ; asymmetrical in the female, owing to 

 the presence, on one side, of a large fleshy leaf-like appendage that 

 forms a brood-pouch. 



Telson and the appendages on either side of it quite symmetrical. 



Eye-stalks stout, of good length : eyes large, reniform : ophthal- 

 mic scales acute. 



Antennules of moderate length. Antennal acicle long and slender 

 antennal flagellum long. 

 J. II. 15 



