Mr. JeflPreys on Bi^itish Mullusca. 39 



these little shells." It is equally abundant in the Channel Isles. 

 The original species (P. Recluzianum) seems to have been founded by 

 M. Bourguignat on young specimens of P. Hensloivinmim (\a,r.pul- 

 chellum) from Boulogne, and is described and figured in the * Journal 

 de Conchyliologie,' t. iii. p. 174. pi. 8. f. )ia-e. 



Mytilus Galloprovinciahs, Lamarck, vi. (1) 126. I believe this to 

 be a distinct species from M. edulis or any of its varieties, and that 

 it may be readily distinguished by the compression and sharp angle 

 of the anterior side, the more rounded outline of the basal margin 

 (which in M. edulis is subquadrate), the beaks being more incurved, 

 and especially by the prominence of the posterior or byssal margin. 

 It also attains a much larger size ; a specimen which I noticed in the 

 collection of M. Deshayes, from Toulon, measuring about five inches 

 in length. Mr. Barlee's specimen of M. edulis, which is recorded in 

 the * British MoUusca' as measuring eight inches and a half in length, 

 is a Modiola modiolus. Another characteristic mark, which I ob- 

 served in Lamarck's typical specimen of M. Galloprovincialis at the 

 Jardin des Plantes, and in all the other specimens which I have seen, 

 is that the epidermis is more or less puckered, like what are called 

 " crows' -feet," in some part or other of the shell. The M. pellucidus 

 of Pennant and other English conchologists is most probably a variety 

 of this species, and not of 3/. edulis ; but I will not venture to restore 

 Pennant's name, as he did not distinguish the species with sufficient 

 precision. It is also probably the M. dilututus of Gray, and the Jf. 

 subsaxatilis of Williamson. It is not uncommon on our coasts ; and 

 I have some fine specimens from the Bristol Channel. A repre- 

 sentation of this species will be found in PI. II. fig. 4. 



M. ungulatus, PI. II. fig. 5. Linn. Syst. Nat. p. 1157. Poli, 

 Test. utr. Sic. t. ii. p. 208. 



While I was at Serk with Dr. Lukis, we found in the Gouliot Caves 

 there several specimens of this unquestionably distinct species, mixed 

 with M. edulis and M. Galloprovincialis. .These caves are completely 

 uncovered by the sea once only in about eight cr ten years, and are 

 never accessible except at low spring tides, and even then for a very 

 short time only ; and the mussels were obtained by scraping the side 

 of one of the outer entrances which was under water. The tide 

 sometimes rises on that coast to a height of 32 feet. The specimens 

 in my possession exactly correspond with the description given by 

 Linnaeus in his ' Systema Naturae,' and which is as follows : — " M. 

 testa Isevi, subcurvata : margine posteriori inflexo, cardine terminali 

 bidentato." And in the ' Mus. Lud. Ulr.' p. 541, he says, "Testa 

 rudis, fragilis, livida, striata transversim quasi ex lineis imbricatis. 

 Sutura postica linea recta excurrit ultra apicem obtusum. (-ardo 

 rima longitudine suturse eique parallela. Par testarum distinctarum, 

 in piano juxta se positarum, refert ungulas pecoris binas medio a se 

 invicem dehisceutes et basi divaricatas." And in his note 136* he 

 adds, " Valvulse valde convexse. Nates distantes acutse. Cardo apicis 

 dentibus 2, 3, s. 4, notatus." The localities assigned by Linnaeus to 

 this species are Southern Europe and the Cape of Good Hope ; but 

 I suspect that the shells from the last-named locality may belong to 



