MYTILUS. MUSSEL. 111 



7- Mytilus ungulatug. Hoof Mussel 



Lister, pi. 360. f. 199 -Donovan, pi. 128. f. 2. 



Shell oblong-oval, very convex thin and brittle, wrinkled 

 transversely, of a greenish or blueish-black color, incurved 

 at the posterior side and much produced at the anterior 

 margin : beaks pointed, incurved, and diverging : hinge 

 with from two to six teeth at the point, besides nume- 

 rous crenulations on the groove : length four inches ; breadth 

 two or more. 



Full-grown shells are very rarely found : but the young 

 ones are covered with a pale oil-green skin, with longitu- 

 dinal or transverse reddish /igza^ lines or blotches, espe- 

 cially on the angular side, and sometimes there is a narrow 

 straight black or brown stripe or two from the beak down 

 the anterior side ; the posterior margrfr is also Straight, 

 with a gibbosity in the middle : these are not uncommon on 

 the Devonshire coasts, v. v. 



8. Mytilus Modiolus. Smooth Mussel. 



Lister, pi. 359. f. 198, and pi. 1057- f. 5 Donovan, 

 pi. 23 Da Costa, pi. 15. f. 5, right hand fig. Dorset Cat. 

 pi. 12. fig. 5,. right hand fig. 



Shell oblong-oval, thick, very convex towards the hinge, 

 covered with a purplish black skin, under which it is white 

 often mixed with flesh-color, strongly wrinkled trans- 

 versely, nearly straight on the posterior side, and very little 

 angular on the other, perlaceous within : beaks very ob- 

 tuse, a little turned to one side, placed laterally, in conse- 

 quence of which there is a gibbosity formed by the protru* 

 sion of the posterior margin, and a slight notch, as in those 

 of the M. incurvatus : hinge without teeth or denticula- 

 tions : length from four to six inches ; breadth half as much. 



Maton and Rackett, and consequently Mr. Dillwyn, have, 

 quoted the two figures 5, in Da Costa's fifteenth plate, in- 

 discriminately both for this species and the M. edulis, al- 

 though Da Costa has pointed out their distinct references. 

 And Mr. Rackett, in his Dorset Catalogue, supposing them 

 to be the same, has omitted the reference to this species 

 from his own plate. 



f 'uriety A. Contracted into a deep intorted rugged cavity 

 below the hinge on the posterior side. 



i, 2 Mytilus 



