MYTILUS. MUSSEL. 
Ill 
7. Mytilus ungulatus. 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 5 breadth 
two or more. 
Full-grown shells arc very rarely found : but the young 
ones arc covered with a pale oil-green skin, with longitu¬ 
dinal or transverse reddish zigzag 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 margin is also straight, 
with a gibbosity in the middle : these are not uncommon on 
the Devonshire coasts, v. v. 
4 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. incurvatits: hinge without teeth or dcnticula- 
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 distinctreferences. 
AGd Mr. Ruckett, in his Dorset Catalogue, supposing them 
to be the same, has omitted the reference to this species 
from his own plate. 
Variety A. Contracted into a deep intorted rugged Cavity 
below the hinge on the posterior side. 
h 2 Mytilus 
