34 
* M, EDULIS. Turt. Lin. Pen. Brit. Zo., vol. 4, pi. 63, 
fig. 33. Mont. Test. Brit., vol. 1, p. 159. Flem. Brit. 
An., p. 411. Common Muscle. Naturalists have not yet 
agreed whether we have one or several species of Muscle I 
it is therefore judged best to speak of the several varieties 
found on our coast, as if they were species, by which 
means we shall avoid the great, though least common 
error, of confounding together several separate kinds : a 
minute examination of the animal of which will alone 
decide the question of their specific identity. 
Or. Fleming’s character of this species refers to the M* 
Pellucidus of Pennant, pi. 63, fig. 75; a variety of common 
occurrence — rather than to the more usual appearance of this 
shell- fish, which is without, longitudinal coloured bauds. Beds 
of muscles are found in harbours and the mouths of rivers, 
where from the frequent change of salt and fresh water, they 
attain their highest perfection ; and from whence they are 
taken for food, and to be used as bait by fishermen. There 
is no shell-fish that so frequently disagrees with the stomach, 
as the muscle; and the symptoms it produces are often of 
the most violent kind. 
M. SUBSAX ATI LIS. Williamson in Mag. Nat. Hist. 
O. S. vol. 7, p. 354. The. difference between this, and the 
long and narrow form of a variety that is of frequent oc- 
currence at Helford, and some other parts of our coasts? 
would indicate specific distinction : but. the more common 
form intermediate between them, is united to either by 
such gradual marks of approach, that nothing beyond 
doubt can be admitted, 
* M. INCURVATUS. Turt. Lin. Pen. Brit. Zo., vol. 4, 
pi. 64, fig. 74. As this species assumes much variety of 
form, it would not he difficult to obtain specimens that 
could not easily he distinguished from some of the common 
muscle; but their habits differ greatly. So far is tb* s 
from seeking, as the former, perpetual immersion, it select* 
a station so high above the low water tide-mark, that in 
many instances it must remain dry for not less than ten 
hours. The chosen crevices also arc more frequently on 
the dry ridge, than in pools; on the summit of the rock 
than at the base. Montagu speaks of it as occurring 
single; but in my observation they congregate in coC' 
siderable numbers 
PINNA. 
GENERIC CHARACTER: Shell longitudinal, wedg« 
shaped, the valves equal, gaping at the summit, pointed at 
the base, the beaks straight, hinge lateral, without teeth- 
Ligament marginal, linear, very long, almost internal. 
* P. JNGENS. Pen. Brit. Zo., vol. 4, pi. 59, tig. 
but marked by mistake P. Fragilis. 31out Test. Br6-t 
