58 MYTILID^I. 



of this family. We may have opportunities of again observing 

 Mytilus, Modiola, and Crenella, but the animals of Pinna and 

 Avicula are not met with on the South Devon coasts in 

 my district of Exmouth; I should therefore be extremely 

 obliged to malacologists who have opportunities of seeing 

 these animals to communicate their remarks. I shall at pre- 

 sent g;ive a short account of them from Poli, which I trans- 



o 



late from M. Deshayes' extracts from that eminent zoologist, 

 in the last edition of Lamarck's ' Animaux sans Vertebres,' 

 to enable naturalists to compare and weigh well their rela- 

 tions with each other, and with the families of the Mytilidte 

 and Ostreadce. 



MYTILUS, Linnaeus. 

 M. EDULIS, Linnaeus. 



M. edulis, Brit. Moll. ii. p. 170, pi. 48. f. 1-4, and (animal) pi. Q. f. 5. 

 M. incurvatus, M. pellucidus, M. subsaxatilis, Auct. 



Animal elongated, thick, subconical; at this season, 5th 

 August, the general colour varies from white to all the hues 

 of orange-yellow, except the foot, and the dorsal and ventral, 

 posterior and anterior extremities of the mantle, which perma- 

 nently exhibit the various shades of a deep reddish brown. 

 The mantle is open from the very large, short, oblong oval, 

 Avhite, simple membranous tube, situated on the upper poste- 

 rior slope, which serves for anal purposes, and a separate 

 branchial communication by a transverse fissure in the in- 

 ternal septum into the ventral cavity, which, though it com- 

 municates with the same common tubular process as the 

 rectum, has no further connexion with the anal conduit. 

 The mantle has a double margin, a plain outer and an inner 

 one, which, from the point of the siphonal tube to the centre 

 of the ventral range, is furnished with tentacular dendroid 

 cirrhi, 15-25, of a pale brown on the main stems, with the 

 ramose subfoliated fimbriae shadowing to pale yellowish white ; 

 the remainder of the ventral range, in which the byssus and 

 foot act, is only broken into long white dentations ; the two 



