Quarterly Journal of Coiic/iology. 369 



the shell, the animal twists its foot about, and on being replaced 

 immediately bores obliquely downwards and disappears from 

 view; the same happens when the shell is merely touched. If 

 hoAvcver the mollusk is lifted up and t\\Qfoot touched, the animal 

 ejects a small stream of water and then twists its foot up, so as to 

 allow of its complete retraction within the shell, a small horny 

 operculum closing the aperture. The animal buries itself, and 

 does so partially when overtaken by a powerful wave, so as to 

 prevent its being carried back into deep water. 



Sometimes gigantic MedusDS, nearly a yard in diameter, are 

 stranded on the shore ; there is then a grand feast, numbers 

 congregate on and around it, while others in the vicinity may be 

 observed hurrying up open mouthed. 



B. rhodostoma may be taken as the type of the S. African 

 littoral species, of which there are several, but the deep water 

 species are very different both in structure and habits. 



PHOLAS CRISP ATA, L., BORING IN METAMORPHIC 



ROCKS. 

 By J. S. GIBBONS, M.B. 

 I found the above species in considerable abundance in decom- 

 posing gneiss near Aberdeen. The live mollusk was not known to 

 Macgillivray when he published his "MoUusca of Aberdeenshire." 



A NORTHERN LOCAEITY FOR H. CANTIANA, Mont. 

 By J. S. GIBBONS, M.B. 

 Newcastle is, I believe, the northern-most point for this 

 species, there however it is supposed to have been introduced 

 with ballast. Some years ago I collected it on the chalk cliffs of 

 Bempton, near Flambro' Head, a locality so retired that it is 

 impossible to suppose it otherwise than indigenous. 



Aug., 1878. 



