TRIBE MYTILACEA. 24.5 
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.! 
M. Ovatis. Lam. 8.—E. t. 219. f. 8. Small, oval, brownish 
violet, not at all angulated, with radiating crenulated sulci; beaks 
obtuse, inclining to one side and diverging. 1.—Peru. 
M. Usruratus. Zam. 9. Small, ovate-angulated, yellowish- 
brown, with radiating sulci which on the anterior side diverge ; 
beaks short and rather obtuse. 3.—Brazil. Dorsal angle distinct. 
The specimens in the Parisian museum bear a strong resemblance to 
the species usually (erroneously) termed Striatutus in cabinets of 
British shells. 
M. Domincensis. Lam, 10.—Del. t. 13. f. 11. Small, ovate 
oblong, posteriorly depressed, purplish violet, longitudinally sul- 
cated ; beaks obtuse and shortened. 2—St. Domingo. 
M. Senecatensis. Lam. 11.—Del. t. 13. f. 10.—l’ Aber Adan. 
Sen. t. 15.—M. Puniceus. Gmel. 3362.—D. p. 313.—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. Gmelin’s name although it 
has priority, is soimexpressive of its real character (for it is rarely 
scarlet or crimson) though undoubtedly the l Aber 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 Linneus. 
M. Nicer. 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 striz, posterior ventral edge 
'Add likewise the Ticuoconta Excisa. Weig. Archi. 1837. Ob- 
long triangular ; angle of the anterior side rounded off, obsolete ; 
deeply striated, strise 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. 193..11. lines. 
Indian Seas.? 
T. Vircata. Wieg. Arch. 1837. 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. Wiecmannt. (VIII. 3. ¢. 2.f. 6 to 10.), and 
T. Kraussu.(VIII. 3. ¢. 6. f. 1 to 6.) in Kusters edition of Chem- 
nitZ. 
