108 PORTUNID^. 



prawn and lobster-pots, but not a specimen of any other 

 species was obtained there. The place of these is supplied 

 at Sandgate by the present species, whilst farther to the 

 west, P. puber^ and P. depurator appear to occupy the 

 ground and perform the same important office of scaven- 

 gers of the sea. 



There is another fact relative to this species which is 

 worth recording, and that is, the extent to which they are 

 infested with a remarkable parasite, occupying the space 

 between the folded abdomen and the sternum, and hav- 

 ing the prima facie appearance of a bag of immature eggs. 

 Both males and females are equally obnoxious to it ; and 

 from its size and situation it must present an insuperable 

 barrier to impregnation. It consists principally of a mass 

 of minute eggs, which are arranged in bundles attached 

 to filaments, like bunches of grapes ; the alimentary canal 

 passes directly through the body, the mouth being at- 

 tached to the intestine of the crab, which it pierces near 

 its extremity, and from which, in all probability, it derives 

 its nourishment. The anal opening, which is distinct 

 and obvious, is visible without removing the parasite from 

 its position. The whole is of a rounded trihedral form, and 

 is covered by a tough but thin integument. I have oc- 

 casionally found it infesting Carcinus mwnas, but never 

 in such numbers as on the present species. 



