TRIBE MYTILACEA. 245 



raised longitudinal sulci which are slightly subcrenulated : beaks 

 acute ; within blue or purplish, a shelly plate uniting the two sides 

 at the hinge which is provided with two denticles in each valve 

 under the apex. 2. Indian Ocean and New Holland. A downy 

 posterior beard in the young. 1 



M. Ovalis. Lam. 8. — E. t. 21 9. f 3. Small, oval, brownish 

 violet, not at all angulated, with radiating crenulated sulci ; beaks 

 obtuse, inclining to one side and diverging. 1. — Peru. 



M. Ustulatus. Lam. 9. Small, ovate-angulated, yellowish- 

 brown, with radiating sulci which on the anterior side diverge ; 

 beaks short and rather obtuse, f. — Brazil. Dorsal angle distinct. 

 The specimens in the Parisian museum bear a strong resemblance to 

 the species usually {erroneously) termed Striatulus in cabinets of 

 British shells. 



M. Domingensis. Lam. 10. — Del. t. 13. f 11. Small, ovate 

 oblong, posteriorly depressed, purplish violet, longitudinally sul- 

 cated ; beaks obtuse and shortened, § — St. Domingo. 



M. Senegalensis. Lam. 11. — Del. t. 13. f. 10. — VAber Adan. 

 Sen. t. 15.— M. Puniceus. Gmel 3362.— D. p. 3\3.— W.t. 12. f. 

 29. Small, narrow, ventricose, usually purplish except at the flat- 

 tened and sinuated posterior margin ; with raised longitudinal sub- 

 crenulated sulci which are scarcely so wide as the interstices : beaks 

 incurved moderately acute, not touching ; hinge margin long, not 

 crenulated internally. |. — Senegal. Gmelins name although it 

 has priority, is so inexpressive of its real character (for it is rarely 

 scarlet or crimson) though undoubtedly the VAber of Adanson from 

 whose description the Puniceus was constituted, that I have preferred 

 leaving the name which Lamarck assigned to this species unaltered. 

 Possibly this shell is the long sought for Bidens of Linnceus. 



M.Niger. Gmel. 3362— D. p. 309.— W. t. 12. f.20.—Le 

 Dotel Adans. Sen. p. 211. t. 15. f 3. Suboval, compressed, thin, 

 black, with crowded minute radiating striae, posterior ventral edge 



l Add likewise the Tichogonia Excisa. Weig. Archi. 1837. Ob- 

 long triangular ; angle of the anterior side rounded off, obsolete ; 

 deeply striated, striae prominent, forked in aged specimens ; brown 

 under a yellowish epidermis : a laminar plate (with a sinus cut out 

 of it) and numerous small denticles at the apex. 19^.. 11. lines. 

 Indian Seas.1 



T. Virgata. Wieg. Arch. \S37.p. 49 Oblong-triangular, pur- 

 plish black, ribs divided at their termination into 3 or 4 smaller ones 

 almost evanescent at the margin : within violet, a laminar plate at the 

 apex, teeth solitary and external, occuping the sinus of the other 

 valve. 20.. 9. lines. Dead Sea.? 



See too the T. Wiegmannii. (VII 1. 3. t. 2./. 6 to 10.), and 

 T. Kraussii. (VIII. 3. t. 6./. 1 to 6.) in Kusters edition of Chem- 

 nitz. 



