Heart-Cockle and Fresh-water Cockle loi 



the crevices of old bivalves, sometimes in the burrows 

 of the Boring - sponge (6Yio7ia) in old oj^ster-valves. 

 Its greatest length is only a couple of lines. The 

 rusty Montagu-shell {M. ferriiginosa) is more oblong, 

 greyish white in hue, but this is hidden by a 

 rusty-looking incrustation that covers the epidermis, 

 and is no doubt due to the peculiar habitat of the 

 creature. The front teeth differ from the back, and 

 the opposite front pair differ somewhat fi'om each 

 other in order that they may interlock. It affects the 

 burrows of the Heart-Urchin (EcJiinocardiurii cor- 

 datum), and often is attached by its byssus to the 

 bristle-like spines of the Urchin, and is dragged about 

 with every movement of the Urchin. 



We have now to briefly describe four small genera, 

 two of them each represented by a solitary species. 

 They are all small, and consequently little known to 

 the average seaside visitor, and have no popular 

 names. We must therefore utilise their scientific 

 names as far as possible. The Globose Kelly-shell 

 (Kellia suhorhiculaTis) is more or less 

 globular, equal-sided, thin, glossy, with 

 faint lines running across from the beaks, 

 and others parallel with the lower margin. 

 The thin and iridescent epidermis gives a 

 greenish hue to the white of the shell. In pended by 

 the right valve the two strong teeth are ^^^""^ 

 laterals ; they are repeated in the left valve with the 

 addition of a cardinal. Both shell and animal are 

 nearly transparent. As shown in the first figure, the 

 mantle extends considerably beyond the shell margin, 

 and its edges are united all round. There is a large 

 opening on the lower margin to allow passage for 



Globose Kelly- 

 shell, 



