H 



24 



CORONULA. 



lepas diadcma. — Linnceus. 



Wood's Conchology, plate 5, page 35. 



This, like the preceding genus, exists on the back of 

 the whale, tortoise, or other marine animals, in which 

 a small portion of it is embedded at the base, and ad- 

 ditionally secured or fastened by small teeth on the 

 lower part of the cells or partitions of the shell. It 

 appears an univalve, but is composed of six longitudi- 

 nally ribbed valves, diverging from the summit to the 

 base, and, with the intermediate spaces, (which are 

 smooth, or finely striated concentrically), dividing it 

 into twelve compartments. The aperture is always 

 regular, and of a rounded oval, or slightly hexagonal 

 form; interior funnel shaped; base open, and divided 

 into eighteen striated partitions or radiating cells, and 

 the operculum divided into four small obtuse valves. 

 The increased size of the shell takes place at thelower 

 extremity or base. 



Corouula diadema Coronula balanaris 



Coronula testudinaria. 



