MODIOLA. 189 



radiations on a rufous ground. The former variety, which 

 is remarkably scarce in Great Britain, we have figured 

 from a very large specimen belonging to Mr. Jeffreys ; it 

 measures quite two inches in length, and displays very 

 characteristically the elongated dorsal margin, a feature 

 which enables us to readily distinguish the adult of this 

 species from Modiolus. The violet rays in this example are 

 almost concealed by the epidermis, but are distinctly visible 

 when the shell is held up to the light. 



The animal is oblong, its mantle is yellowish- white, plain- 

 edged, freely open in front, and round as far as the distinctly- 

 formed but short anal tube ; the branchial region is slightly 

 pouting, and quite plain. The foot is cylindrical, bluish- 

 white, and grooved along its length. The byssus is yellow- 

 ish. The branchiae are pale brown. 



This species is an inhabitant of our western shores, and 

 is sparingly distributed, yet by no means uncommon. 

 Channel Islands (S. H.); West bay of Portland in fifteen 

 fathoms, gravel, and in seven fathoms at Dartmouth 

 (M'Andrew and E. F.); Exmouth (Clark); Torquay 

 (S. H.); Milford Haven in ten fathoms, and Anglesey in 

 from seven to forty fathoms (M'Andrew and E. F.). In 

 forty-five fathoms off Foula, Zetland (M'Andrew.) "Very 

 rare on the Irish coast, but obtained on each side of the 

 Island." Belfast Bay (Mr. Hyndman and W. T.); Mala- 

 hide and Portmarnock (Dr. Lloyd and Mr. Warren) ; 

 Birterbuy Bay, "Dr. Farren " (W. Thompson); Bantry 

 Bay in fifteen fathoms (M'Andrew). 



It ranges to the Mediterranean. 



