478 PROCEEDINGS OF THE ACADEMY OF 



Hub. "Ad Insulas Gallapagos et apud Insulam Lord Hood's dictarn. 

 Found in pearl oysters, in from three to seven fathoms." Sowerby. 



2. R. denticulata, Deshayes, sp. 



Gastrochaena denticulata, Deshayes, Zool. Proc. Lond. p. 327, 1854. 

 Rocellaria denticulata, H. and A. Adams, Genera, ii. p. 336, 1856. 



Description. "R. testa ovato-ventricosa, brevi, solidula, lata, hiantissimi, 

 hiatu ovato, lato, inferne attenuato et tertiam partem posticam testae attin- 

 gente ; valvis subtrapezoidalibus transversim striato-lamellosis, in latere 

 antico striis imbricatis, crispato-denticulatis, in latere postico erectis, distan- 

 tioribus ; latere antico satis elongato, recto, in sutura, cristato ; umbonibus 

 tumidulis, subumbilicatis ; ligamento angusto, elongato, fulvo." Deshayes. 



Hab. Columbia. Coll. Cuming. 



This is a heavy shell, while R. b r e v i s is thin and pellucid. It is also 

 more prominently striated than that species, and differs from it in shape. 



3. R. dubia,* Pennant, sp. 



Mya dubia, Pennant, Brit. Zool. iv. p. 82, t. 44, f. 19, 1777. 

 Donovan, British Shells, iii. t. 108, 1810. 

 Maton and Rackett, Linn. Trans, viii. p. 33, 1807. 

 Wood, Gen. Couch, p. 102, t. 25, f. 2, 3, 1815. 

 " Index Test, edit. 1, p. 11, 1818. 

 " " " edit. 2, t. 2, f. 23, 1828. 



Gerville, Cat. des Coq. de la Manche, p. 10, 1825. 

 Mya Pholadia, Montagu, Test. Brit. i. p. 28 et 559, et supp. p. 20, 1803. 



Fleming, Edinb. Encyc. ii. p. 87. 

 Chama parva, DaCosta, Brit. Conch, p. 234, 1778. 

 Pholas faba, Pultney, Dorsetshire Catalogue, p. 27, 1799. 

 Pholas pusilla, Poli, Test. utr. Sicil. i. p". 50, t. 7, f. 12, 13, 1791. 



Olivi, Aclrit. p. 93, 1792. 

 Mytilus ambiguus, Dillwyn, i. p. 304, 1817. 



Balano minimo, Ginanni, Op. post. ii. p. 35, t. 23, f. 164, 1755 '57. 

 Gastrochcena Pholadia, Turton, Conch. Dithvra Brit. p. 18, t. 2, f. 8, 9, 



1822. 

 Lukis, Loudon's Mag. Nat. Hist. vi. p. 404, f. 52, 



1833. 

 Brown, Illust. Brit. Conch. 2d ed. p. 116, t. 48, 

 f. 13, 14, 1844. 

 Gastrochaena hians, Fleming, Brit. Anim. p. 458, 1828. 

 Gastrochaena cuneiformis, Philippi, Enum. Moll. Sicil. i. p. 2, 1836. 

 Gastrochaena Polii, Philippi, Enum. Moll. Sicil. ii. p. 3, 1844. 



Requier, Cat. des Coq. de la Corse, p. 13, 1848. 

 Gastrochaena (Chaena) faba, Gray, Figs. Moll. Anim. v. p. 28, t. 339, f. 2, 



3, 4 ; t. 347, f. 68, 1857. 

 Gastrochaena modiolina, Lamarck, Anim. Sans Vert. v. p. 447. 1818. 



" (Desh. edit.) Anim. Sans Vert. vi. p. 



49, 1835. 

 Sowerby. Genera, f. 1, 2, 1820 '24. 



" ' Conch. Manual, f. 52, 1842. 

 Crouch, Introd. Lamarck, t. 2, f. 12, a, b, 1827. 

 Bouchard-Chantreaux, Moll. Boulonnais, p. 8, 



1829. 

 Collard de Cherres, Cat. Test. Mar. p. 9, 1830. 

 Hanley, Desc. Cat. p. 10, 1842. 

 Cailliaud, Guerin's Mag. Zool. Moll. p. 2, t. 69, 



70, 71, 1843. 

 Reeve, Conch. Syst. t. 50, f. 1, 2, 1843. 

 Potiez et Michaud, Gallerie des Moll. ii. p. 268, 

 1844. 



[Dec. 



