PLATE XXIIII. 



My tilus Modiolus is the largest species of this genus that inhabits the 

 British shores ; being from six to seven inches in length, and three in 

 breadth. It is a strong and heavy shell ; the outside is of a blackish 

 colour inclining to purple. It is covered with a thin filmy brown 

 epidermis, and often with balani and other remains of crustaceous 

 animals. Within, it is smooth and pearly, and sometimes richly 

 coloured with a variety of vivid hues, in which red, purple and green 

 chiefly predominate. These shells lie only in deep waters, and are 

 never cast upon shore ; but sometimes they seize the bait of the 

 ground lines, and are hauled up by the fishermen. 



Da Costa received the M. Modiolus, of a fmall size, from the 

 Margate flats in Kent ; from Cornwall and other English shores. 

 The specimen figured in the annexed Plate is from Scarborough in 

 Yorkshire ; thofe found on the coast of Wales and Scotland, and 

 particularly the Orkneys, are not inferior in point of size to those 

 from Scarborough. 



