162 TESTACEOUS MOLLUSCA. 



PECTUNCULUS. 



Orbicular ', doubly convex, equivalve, subequilateral, and close ; 

 hinge arcuated, teeth numerous, oblique, serrated, alternately 

 inserted into the opposite valves, middle ones obsolete ; ligament 

 external. 



* Surface not ribbed. 



P. Pilosus.* Lam. 2. — Philip, p. 61. — Arca P. Lin. — W. 

 t. 9.f. 37. — P. Glycimeris. Undatus 8? Pilosus. Turton. Biv. 

 t. 12. f. 1, 2, 3, 4. — P. Marmoratus. Lam. 4. — Arca P. D.p. 

 242.— W. t. 9. f. 36.— Arca M. Gmel. 3314.— Ch. f. 560. f 

 563.— List. t. 247. /. 82.— Knorr. 6. t. 14. /. 4.— Gualt. t. 72. 

 G. — JE. t. 310.y. 3. Orbicular-ovate, becoming inequilateral by 

 age, white with angular red streaks arranged either longitudinally 

 or transversely (sometimes flesh colour with white spots and an- 

 gular red ones) minutely decussated, the apices obliquely incurved, 

 approximate : inside white or whitish : epidermis velvety. 1|. — 

 Atlantic and Mediterranean. 1 



P. Siculus. Reeve. Ic.f. 41. — P. Glycimeris. Lam. I. — 

 Philip, p. 60. — P. Pilosus. Sow. G. — Reeve. Sys. t. 83. f. 1. — 

 Ch.f. 564.— Poli. t. 25. /. 17, 8 ?—List. t. 247. f 82 ? Orbicular, 

 rather broader than long, all but equilateral, rather depressed 

 (except when aged) uniform, brownish red (usually with darker 

 zones and the beaks often tipped with white) radiated by 

 minute striae and delicate pale rather distant lines having the 

 appearance of obsolete sulci : epidermis silky, brown. 3. — Medi- 

 terranean. 



P. Undulatus. Lam. 3. — Del. t. 12. f. 1. — Arca Undata ? 

 Lin. — Brug. Die. p. 114? Ovate orbicular, tumid, inequilateral, 

 anteriorly angulated and the longitudinal furrows very apparent : 

 white with small waved rufous spots disposed in transverse rows : 

 beaks with a straight inclination to each other. 1|-. — America? 



P. Scriptus. Lam. 5. — Reeve, Ic. f 6 ?? — Arca Scripta. 

 D.p. 243.— Born. t. 6.f 1. a.— List. t. 246. f. 80.— i£. t. 311. 

 f. 8. — W. t. 9. f. 39. Orbicular, rather depressed, with minute de- 

 cussated strise, whitish with angular fulvous lines ; beaks slightly 

 curved anteriorly : within white stained with yellow at the anterior 

 end, crenations of the margin about fifty and only visible in the 

 centre. 1-J. — St. Domingo. 



1 From an examination of LinnoBUs^s own specimen, I can 

 safely assert that M. Deshayes is in error in considering this shell 

 to be the Glycimeris of Linnceus. The specimens of the latter 

 are the Violascens of Lamarck. 



