1922.] S. Kemp : Notes on Crustacea Decapoda. 117 



pass through the small apertures in the test of the Ascidian. 

 They are thus, like Spongicola venusta in Euplectella, perpetual 

 prisoners. 



In the course of an extremely interesting note on sex-pheno- 

 mena in Pinnotheres , Orton ' has pointed out that female crabs are 

 frequently found alone in a mollusc and that males are scarce. 

 This corresponds with my own observations on this and other gen- 

 era of Pinnotherid crabs in India : single specimens, usually females, 

 are of common occurrence and it is quite exceptional to find two 

 crabs in one mollusc. It is probable, as Orton has pointed out, 

 that the male crabs wander freely and visit the molluscs from 

 time to time in search of females. 



Conditions are different with the Pontoniids that live in 

 Lamellibranchs, for in practically every instance a male and 

 female prawn are found together in the same mollusc. From this 

 fact it is perhaps legitimate to infer that, as with the species in 

 Ascidians, the prawns after they are once established in their host 

 never leave it throughout the whole course of their existence. 



The animal associations recorded in the Pontoniinae are the 

 following: — 



On PORIl'ERA. 



? Periclimenes impar, sp. nov. 

 Pontonia tyrrhena (Petagna). 2 

 Typton spongicola Costa. 



On COELENTERATA. 



On Actiniaria. 



Periclimenes brevicarpalis (Schenkel),on Discosoma. 

 ,, inornatus, sp. nov., on Discosoma. 



On Madreporaria. 



Periclimenes spiniferus de Man. 

 ,, diver sipes, sp. nov. 



Harpilius, probably all species. 

 Coralliocaris, probably all species. 

 On Alcyonaria. 



Periclimenes investigator is t sp. nov. 



,, diversipes, sp. nov. 



Dasycaris symbiotcs, gen. et sp. nov., on Pteroeidcs 

 Pontonides beauforlensis (Borr.), on a Gorgonian. 

 Balssia gasti (Balss), on Corallium rubrum. 



On ECHINODERMATA. 



On Asteroidea. 



Periclimenes parasiticus Borr., on Linckia. 

 On Echinoidea. 



Periclimenes brocki de Man. 



Stegopontonia commensalis Nobili, on Echinothrix. 



1 Orton, Nature CVI, p. 533 (1920). 



2 Fide Heller. The species usually lives in Pinna and it seems to me 

 little unlikely that it should also occur on sponges. 



