oe TESTACEOUS MOLLUSCA. 
Janeiro.—The Oblonga of Say, in Journ. A. N. 8. Phil. 2, and the 
Californica of Conrad, in the seventh vol. of the same work, are (to 
say the least) closely allied to this species.1 
M. Petiucipa.* Chem. f. 234.—D. p. 144.—M. Depressa. 
Lam. 29.—M.Deaupata. Mont. p. 95. t. 5. f. 1.—W. t. 6. f- 
32. Sub-ovate, thin, pellucid, white and convex; disc smooth and 
depressed, the sides with somewhat plait-like strie.— Brazil. 
M. Lisor. Adanson Senegal. t. 17. f. 16. Ovate-triangular, 
rather longer and more acuminated anteriorly ; thin, polished, 
smooth but grooved on the flattened slopes and towards the posterior 
ventral edge ; umbones rather distant ; lateral teeth, thin, laminar, 
moderately distant ; either pale fulvous with linear livid rays and 
the beaks and interior violet, or uniform white, or white with lac 
zones and violet beaks, under which is a dark stain internally. 
4..11.—-Senegal, 5.2 
M. Trigonetia. Lam. 31.—F. 259. f. 2? Triangular inequi- 
lateral white ; hinge with the teeth if any indistinct.— Bay of Sea 
Dogs. 
M.Truncata. Mont. Sup. p. 34.—Turt. Biv. p. 68.—An. 
M. Triancuuaris. Ranieri?—M. Susprruncata.. Don. t. 
126.—M. CrassateLtna. Lam. 33. ‘Triangular, equilateral, 
solid, convex, anteriorly sub-angulated, depressed from the beaks at 
both extremities, so that the sides almost form a rectangle at the 
prominent beaks, ventral edge short and rounded; yellowish white, 
irregularly striated by the lines of growth ; umbones large and pro- 
minent ; slopes and lateral teeth striated. 14..13.—N. Europe. 
M. Sustruncata.* Mont. Sup. p. 93. t. 27. f. 1.—D. p. 
141.-—-Turt. B. p. 70.—W. t. 6. f. 23.—Flem. p. 427. Oval- 
triangular, inequilateral, convex, whitish or yellowish horn colour, 
with regular coarse transverse strie; one side truncated, the other 
produced ina straight line to arather acute point ; beaks tumid, pro- 
minent without curvature ; lateral teeth striated. $..1.—England. 
M. Ausrrauis. Sow. in Beech. Zool. p. 154. an. t. 44. f. 6? 
Subtrigonal, ovate, convex, rounded and rather shorter posteriorly, 
attenuated and obtusely angulated anteriorly, the ventral edge much 
arcuated: white under a thin ashy epidermis, polished and nearly 
smooth: anterior slope obtusely defined, and the edge sloping 
outwards ; both depressions somewhat grooved: inside pure white, 
the lateral teeth large, moderately distant and entire. 14..1}.— 
Swan River. 

1M. Donacia, Lam. 28, belongs to MEsopEsMa. 
2 This latter variety is probably the Lilacea of Lam. 30. Ovate- 
triangular, solid, violet-white with violet beaks and zones, smooth, 
but towards the ventral edge, plicated ; within with a large fulvous 
spot beneath each beak. 
