M 



* M. EDULIS. Tort Lin. Pen. Brit. Zo., vol. 4, pi. 63, 

 fig. 33. Mont. Test. Brit., vol. 1, p. 159. Flem. Brit. 

 An. j p. 411. Common Muscle. Naturalists have not yet 

 agreed whether we have one or several species of Muscle ; 

 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. 



Dr. 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 bands. 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. SUBSAXATILIS. 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 be difficult to obtain specimens that 

 could not easily be distinguished from some of the common 

 muscle ; but their habits differ greatly. So far is this 

 from seeking, as the former, perpetual immersion, it selects 

 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 are 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 con- 

 siderable numbers 



PINNA. 

 GENERIC CHARACTER: Shell longitudinal, wedge 



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. INGENS. Pen. Brit. Zo., vol. 4, pi. 59, fig. 80; 



but marked by mistake P. Fragilis. Mont Test. Brit., 



