MYTILUS. 117 



row, much sunk : Tiinye-plate thin, with a deep ligamental 

 groove beneath it, which is supported by a strong rib : hinge 

 toothless, reflected : inside nacreous and iridescent, sometimes 

 red or tinged by the outside rays : scars rather distinct. L. 1-2. 

 B. 07. 



Var. ovalis. Shell much larger and narrower, almost cylin- 

 drical, more solid ; ventral margin slightly incurved : colour 

 yellow, with dark-purple rays : epidermis horncolour or 

 brownish-yellow. L. 2. B. 0-85. Modiola ovalis, Sowerby, 

 111. Ind. Brit. Shells, pi. 7. f. 7. 



HABITAT : By no means rare, although not common, 

 in the South of England and the Channel Isles, as well 

 as on the coasts of North and South Wales and Ireland, 

 in 740 fathoms, muddy gravel or sand. I know of only 

 three localities for it in Scotland, viz. Firth of Forth 

 (Forbes) ; off Foula, Zetland, in 45 fathoms (M'An- 

 drew) ; and Loch Carron, Ross-shire, in 28 fathoms 

 (J. G. J.). A specimen dredged by me in the last-men- 

 tioned place is of a uniform pale yellow and much larger 

 than those from the south, as might have been expected. 

 The variety is rather plentiful in one part of Falmouth 

 harbour ; and I have also taken it off Guernsey, but of 

 small size. The same variety occurred in excavating 

 a channel in Belfast harbour, and may be considered a 

 newer pliocene fossil. Lilljeborg has found this species 

 in Finmark, Malm on the coast of Sweden in 10-15 

 fathoms (in one case attached by the byssus to Corallina 

 officinalis], and Hsellebsek on the Baltic coast of Zea- 

 land. Its distribution southward extends to the .ZEgean 

 and the Gulf of Tunis, at depths varying from 2 to 50 

 fathoms. 



This prettily painted mussel often makes in its young 

 state a case like that of M. modiolus. When the animal 

 is dead, the shell floats on the surface of water, by 

 reason of its lightness and being perhaps buoyed up by 



