NATURAL SCIENCES OP PHILADELPHIA. 217 



Jouannetia pectinata, Gray, Ann. and Mag. Nat. Hist. 2d ser. viii. p. 383. 



H. and A. Adams, Genera, ii. p. 330. Fischer, Journ. Conch. 2d ser. 



iii. p. 51. 

 Triomphalia pulcherrima, Sowerby, Zool. Proc. p. 161, 1849. Sowerby, 



Monog. Triomph. Thes. Conch, ii. p. 501, t. 106, f. 58, 59. 

 Jouannetia pulcherrima, Chenu, Man. ii. f. 37. 

 Hab. California. W. Colombia. 



Genus Maktesia, Leach. 



Martesia, Leach, MSS. Blainville, Diet. Sci. Nat. 1824. Blainville, Malacol. 



p. 632, 1825. Gray, Zool. Proc. p. 188, 1847. Gray, Ann. and Mag. 



Nat. Hist. 2d ser. viii. p. 380. 

 Mactresia, Gray, Syn. Brit. Mus. p. 91, 1842. (Typographical error.) 



* Valves with two impressed ribs, the hinder one oblique; the anterior dorsal mar- 

 ginal reflection depressed. Gray, Ann. and Mag. Nat. Hist. p. 383, 1851. 

 M. branchiata, Gould. (Sp.) 



Pholas branchiata, Gould, Bost. Proc. p. 290, 1845. Jay, Cat. p. 9. 

 Sowerby, Monog. Pholas, Thes. Conch, ii. p. 493, t. 108, f. 82, 83. 



Martesia branchiata, Gray, Ann. and Mag. 2d ser. viii. p. 383. H. and A. 

 Adams, Genera, ii. p. 331. Fischer, Journ. Conch. 2d ser. iii. p. 52. 



Hab. Africa. 



Coll. J. C. Jay, M. D. 



This shell differs from the following in the dorsal plate being bilobed pos- 

 teriorly, around a portion of the dorsal posterior integument, and in the 

 absence of radiating crenulations on the anterior third of the surface of the 

 valve. 



M. calva, Sowerby. (Sp.) 



Pholas calva, Sowerby, Proc. Zool. Soc. p. 69, 1834, and p. 162, 1835. 

 Sowerby, Monog. Pholas, Thes. Conch, p. 493, t. 105, f. 5153. 

 Catlow, Conch. Nomenc. p. 3. Muller, Syn. Test. Viv. p. 237. 

 Hanley, Desc. Cat. p. 7. 



Parapholas calva, Carpenter, Mazatlan Shells, p. 9. 



Martesia calva, Gray, Ann. and Mag. viii. p. 383. H. and A. Adams, Genera, 

 ii. p. 331. Carpenter, Rep. on W. Coast Mollusca. Chenu, Man. ii. 

 f. 45 47. Fischer, Journ. Conch. 2d ser. iii. p. 52. 

 Pholas acuminata, Sowerby, Zool. Proc. p. 70, 1834. Sowerby, Monog. 

 Pholas. Thes. Conch, ii. p. 492, t. 105, f. 4850. Catlow, Conch. 

 Nomenc. p. 3. Hanley, Desc. Cat. p. 8, t. 9, f. 30. Jay, Cat. 4th ed. 

 p. 10. Muller, Syn. Test. Viv. p. 237. 

 Parapholas acuminata, Gray, Ann. and Mag. Nat. Hist. 2d ser. viii. H. and 

 A. Adams, Genera, ii. Carpenter, W. Coast Report, Check List, and 

 Mazatlan Shells, p. 12. 

 Martesia acuminata, Chenu, Man. ii. f. 56. 

 Parapholas bisulcata, Conrad. Journ. Acad. Nat. Sci. 2d ser. i. p. 279, t. 39, 



f. 5. 

 Hab. California. Mazatlan. Panama. 



Cab. Acad. Nat. Sci. Cab. J. C. Jay, M. D. Cab. G. W. Tryon, Jr. 

 The very variable nature of the dorsal plate has caused the erection of three 

 species for this shell. Mr. P. P. Carpenter, in his Catalogue of Mazatlan 

 Shells, says of P. acuminata, "The author of this species distinguishes it 

 from calva by the shape of the laminse and posterior portion, which are 

 variable in both forms, and by the character of the umbonal shield. This last 

 is the only constant character of difference. It is not only smaller, not pro- 

 jecting beyond the dorsal plate, (which is not the result of age, being found in 



1862.] 15 



