SAXICAVA. 89 



corresponding to tlio S. rhomhoidcs of Deshayes, the M/jfilus prcB- 

 cisus of Montagu, and doubtless the Hiatella arctica of Lamarck 

 {Suh'n initiNfKS, Lin.). 



Now all those varieties are found living jiromiseuously together, 

 and, as their shape is known to be greatly niodilied by the circum- 

 stances under which they are developed, the rational conclusion is, 

 that they all pertain to the same species ; and the probaljility is, 

 tliat they are identical Avith the European shell ; but under what 

 name to place them, and whether mider one or more, it is now im- 

 possible to say. 



[It is now quite possible to say that the shell of the American At- 

 lantic coast is identical with that of the European and Arctic shores. 

 It is so multiform that Woodward states that five genera and fifteen 

 species have been manufactured out of varieties and conditions of 

 this protean species. Two species are generally admitted which, in 

 their early stages at least, greatly resemble each other in the two 

 spinous ridges along the posterior dorsal margin. But they are said 

 to have a constant difference in the anterior end, and in the pres- 

 ence or absence of an areolar space in front of the beaks. We 

 give a pretty extended synonymy of the two, according to latest 

 authorities. 



Saxicava arctica. 



Shell oblong, beaks at anterior fourth, rostrate in front, with a distinct areolar 

 space in front of the beaks ; diagonal ridge spinous. 



Mya arctica, Lin. Syst. Nat. 1113. — 0. Fabr. F. Groenl. 407. — Turtox, Conch. Diet. 



104.— Wood, Gen. Conch. 95. 

 Solen miniitus, Lin. Syst. Nat. lll.'i. — Mont. Test. Br. 53, pi. 1, fig: 4. — Turt. Conch. 



Diet. 161. — CuEMN. Conch. Cah. vi. 67, pi. 6, tigs. 51, 52. — Wood, Gen. Conch. 



139, pi. 34, figs. 5, 6. — DiLLW. Recent Shells, i. 69. — Lam. An. sans Vert. 2cl 



ed. vi. 57. — Wood, Index Test. pi. 3, fig. 33. 

 Mytihis pracisus, Mont. Test. Brit. 165; Linn. Trans, viii. 112. — Dillw. Recent 



Sliells, 305. 

 IliateUa arctica. Lam. An. sans Vert. 2d ed. vi. 443 — Flem. Br. Anim. 461 ; Br. Mar. 



Conch. 59. — Crouch, Introd. pi. 8, fig. 6. — Hanley, Recent Shells, 150. — Cuv. 



R. Anim. pi. 110, fig. 1. 

 Anatina arctica, TuRT. Dyth. Brit. 49, pi. 4, figs. 7, 8 ; Br. Mar. Conch. 42. 

 Agina purpurea, Turt. Dyth. Brit. 54, pi. 4, fig. 9 ; Br. Mar. Conch. 60. 

 Solen purpureus, Flem. Brit. Anim. 459. 



Saxicava purpurea. Brown, 111. Conch. Brit. 103, pi. 42, figs. 30, 31. 

 Saxicava rubra, Desh. Exped. Alger. Moll. pi. 66, figs. 18, 19 (shell and animal). 

 Saxicava rhomlmdes, Desii. in Lam. An. sans Vert. 2d ed. vi. 153. 

 Saxicava arctica, Desh. Elem. Concli. pi. 12, figs. 8, 9. — Phil. Moll. Sicil. i. 20, pi. 3, 



fig. 3, ii. 19. — Macgilliv. Moll. Aberd. 285. — Loven, Ind. Moll. Succ. 40. — 



Chenu, Man. de Conch. 25, fig. 113. 



