298 TESTACEOUS MOLLUSCA. 
subtruncated at the apex, violet-brown; the lamelle so arranged as 
to form indistinct radiating sulci. 14. Timor. The umbones are 
stated to be smooth and white; but the solitary type (evidently imma- 
ture) is too rubbed for this to be regarded as a characteristic. 
O. Tunipa. Lam. 10. Oval-oblong, rather thin, tortuous, violet ; 
upper valve not flat, with somewhat scabrous longitudinal sulci: 
lower valve rayed with white and red: inside white. 2. Hab ? 
* Probably a variety of MytttorpEs” (Desh.). The type reminds me 
of certain specimens of RutzopHoR#.! 
O. ScaBra. Lam. 12. Oblong, spatulate, thin, subpellucid, 
whitish, armed with longitudinal prickly strie. 2. America. The 
type in the French Museum is referred to the genus PLACUANOMIA of 
Broderip. I unfortunately neglected to examine the specimen. 
O. Rostratis. Lam. 13. Oblong, thin, imbricated by loose 
lamelle, tawny-grey tinged with violet, sharp at the beaks, which are 
white, small, subequal, approximate, inclined to the left; posterior 
depression gaping. 14. America. Valves of nearly equal length. 
O. Parasitica (in part). Gmel. 3336.—Lam. (in part) 14.—Desh. 
in H. 2, p 295.—O. Arporgea, Ch. f. 881?—D. p. 279.—W. t. 11, 
J. 712—O. Rurzorvore, Guilding, Z. J. 3, p.542.—Conch. Mis. O. 
t.1,f.1,4. Ranging from ovate to elongated oblong, thin, glabrous, 
parasitical, generally broader and more or less rounded at the base ; 
upper valve more or less depressed, covered (when perfect) with thinly- 
spread, very flat and not at all curly imbricated flakes, which are either 
variegated with radiating purplish brown lines or markings on a ground 
of yellowish white, or are chocolate-brown with a few whitish or yel- 
lowish rays: lower valve deeper and more ample, rayed with white 
and brownish or reddish purple, armed with a few distant radiating 
ribs that are adorned here and there with more or less obsolete elevated 
scales, often with a few loose concentric lamelle: inside whitish, 
showing the external colouring towards the edges, which are neither 
laciniated nor denticulated: cartilage green, its cavity shallow. Up 
to 4. W. Indies, on the roots of the mangrove. Some individuals 
with a linguiform shape and a truncated base answer the description of 
O. Lineva. The Honduras variety, of an uniform dirty purple, and 
with the ribs almost, if not wholly, obsolete, may prove identical with 
O. TuLipa. 


1 QO. Brasrutana. Lam. 11. Thin, oval, dilated above, small, 
somewhat rayed with white on a fulvous ground: upper valve slightly 
convex: transverse striz very fine. Brazil. The type (a small flat 
shell), surmised by Deshayes to be a variety of BoREALTs, ts too young 
to exhibit the permanent characteristics. 
