MYTILTJS. 117 



row, much sunk : hinge-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. 0-7. 



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 7-40 fathoms, muddy gravel or sand. I know of only 

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

 (Forbes) j off Foula, Zetland, in 45 fathoms (M f 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 iEgean 

 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 



