346 Dr. W. C. M'Intosh on the 



less mobile situations. Fine tufts of Sertularia pumila and 

 Crisia ehurnea adorn the surface of the carapace in others or 

 the parasitic algae thereon ; while IlaMcJiondria panicea forms 

 a thick rugged crust, from which Balani^ Seijmlce^ AnomicBy 

 zoophytes, and seaweeds emerge. Even the sockets of the 

 eyes are invaded by the sponge. Moreover young examples 

 are not unfrequently clothed with thick tufts of Ohelia geni- 

 culata. It w^ould appear that it is not always on attaining 

 full growth that moulting ceases for considerable intervals, 

 since small specimens are found as completely covered with 

 parasitic growths. In the rock-pools the carapace often forms 

 a moving forest of seaweeds ; and in such specimens the shell 

 is frequently fragile, so that the extraneous covering may be 

 of use for protection, or else had grown with unusual rapidity, 

 even before the carapace became fully consolidated. 



One old example had the internal antennae quite fixed by a 

 hard sand-tube of Sahellaria ; and the young of the common 

 mussel are occasionally found in the cavities for the eyes. 



In the young females the genital apertures are small, and 

 the abdomen less developed ; while in the adult the latter 

 becomes hypei-trophied, hollowed out on its ventral surface by 

 the bending downwards of the outer edges, and touches the 

 bases of the legs on each side. 



Hyas coarctatus, Leach ; Bell, op. cit. p. 35. 

 Common in deep water, and procured in hundreds amongst 

 the coralline d(5bris in the fishing-boats ; frequent in the 

 stomachs of cod, haddock, and flounders. 



Fam. LeptopodiadsB. 



Genus Stenorhynchus, Lam. 



Stenorhynchus rostrafus, L. ; Bell, op. cit. p. 2 

 (as S. phalangium). 

 Abundant in the coralline region, in the stomachs of cod 

 and haddock, and occasionally under stones at low water. 

 Fragments of sessile-eyed Crustacea and sand occurred in the 

 stomachs of those examined. Males greatly preponderate. 



Fam. Parthenopidse. 

 Genus Eurynome, Leach. 

 Eurynome aspera^ Penn. ; Bell, op. cit. p. 46. 

 A few specimens were procured from the coralline ground. 

 Eare. 



