THE MOLLUSCA 197 



are furnished with stiff, branched hairs or bristles. It 

 lives, firmly fixed, in rock crevices at extreme low water, 

 among sponges, etc., and the hairs retaining a layer of mud 

 and silt help to conceal it. 



There are several other species, some of which live 

 embedded within the cartilaginous tests of large ascidians. 

 These are of small size half to one inch in length. 



Nucula nitida and Nucula nucleus (the " Nut Shells "), 

 solid-looking, strongly angular little bivales, are common 

 all around our shores, on muddy and fine sandy bottom. 



Pectunculus glycemeris (the " Marbled Cockle "). This 

 is a nearly orbicular, very solid shelled bivalve, found 

 abundantly in shelly gravel all around the coasts. It is 

 about an inch and a half across, the colour pale buff, 

 with wavy red markings. 



This mollusc has the power of leaping (which is common 

 to all the " cockles ") very highly developed. By the 

 smart projection of its foot against the ground it can 

 throw itself a distance of five or six yards. 



I remember that once, when a lad, I was sand-eeling by 

 moonlight on the large shell -gravel reaches of the eastern 

 coast of Jersey, when splashes in the water in front of me, 

 and presently a knock on the back, made me think I was 

 being pelted. My consternation was great, as there was 

 not any person in sight, and it was some time before I 

 discovered the cause. This was Pectunculus emerging from 

 the gravel, and leaping seawards to meet the now incoming 

 tide. They were jumping thus in hundreds. 



Area lactea and Area tetragona (the "Box Shells") are 

 strongly angular bivalves, from half to one inch across. 

 They live at low water, where there is broken stone mixed 

 with gravel. They must abound in some parts of the 

 Channel, for the well-known shell beach of Herm Island 

 is mainly composed of their valves. 



A form almost too rare to be mentioned in an " out- 



