354 



Rare British Mytilus, 



eastern coasts of Yorkshire and Durham, and has been ar- 

 ranged under the different names of M. angulatus and M, 

 solitarius. Nothing has, however, been known of its habits, 

 in consequence of the specimens (which have been generally 

 found attached to the roots of seaweeds) being so rare, and 

 all of them young ones, until lately, when a habitat of this 

 species was discovered a little to the north of Scarborough. 

 The only other species to which it bears any resemblance 

 are the M. edulis and the M. incurvatus, both of which are 

 found in the neighbourhood. In the drawing {^fig* 48 ), « is a 



lateral representation of a full grown shell, and d is the 

 anterior margin of the same. From the M. edulis, to which 

 it approaches in size, it differs in the greater thickness of the 

 shell, which is strong and solid; the hinge-line is longer, and 

 very straight, giving rather a rhomboidal form to the valves, 

 sometimes even more so than in the figures; while in the 

 M. edulis it is curved ; the anterior margin is broad, de- 

 pressed, and a little convex, instead of being produced ; the 

 lines of growth are also comparatively stronger. In form, it 

 bears a greater resemblance to the M. incurvatus ; but the 

 latter wants the straight hinge-line, and is not of half the 

 .size. The young shells {b and c) have the character of the 

 hinge even more striking, and are of a deep brown colour, 

 instead of the dirty blue of the old ones. Still stronger 



