Report on the zoological collections made in the Indo-Pacific Ocean ...

MOLLUSCA. 107given bjr Quoy and Gaimard of their Psammohia vitrea and with thefigure in Mobius's work above referred to, pi. xxi, figs. 10 a, h. Thefoot protrudes at the narrower end of the shell ; it is small whenretracted, of a boot-like form, roundly carinate at the base, pointedat the tip, and furnished with what is probably a byssiferous processat the posterior end (" talon," Q. & G.) ; this is of an opaque whitecolour. The mantle is open in front and the anterior half of theventral margin for the passage of the foot, and united along therest of the basal and hinder margins, where there is a minutesiphonal perforation. The surface of the mantle beneath is coveredwith papillae, and the membranous marginal expansion in life probablycovers nearly the entire surface of the shell, for even in spiritspecimens it still extends halfway up the valves. There are twolabial palpi on each side. From this description the close relationshipwith Galeomma is very apparent.The dentition of this species, according to my observation, doesnot agree with the description given by Deshayes. In the rightvalve I find a prominent tooth a little in front of the beak, and asecond more remote behind it ; the left valve has two teeth, ofwhich the anterior is the smaller, just beneath the umbo, and athird a little behind it. The ligament is externally visible, beingattached to the hinge-line above the teeth, a portion of it beinginternal above and between the teeth.48. Scintilla alberti. (Plate VII. figs. G, G 1.)Shell small, pellucid, milky white, considerably inequilateral,transversely oblong, shorter and narrower in front of the iimbonesthan behind them, moderately swollen. Lateral and dorsal marginscurved, ventral rather rectilinear. Surface glossy, exhibiting(under the lens) distinct concentric lines of growth and also minuteradiating and somewhat interrupted striaj, visible oulj^ under acompound microscope. Ilmbones small, slightly elevated above thehinge-margin, not quite adjacent, the valves being closed. Cardinalteeth insignificant, consisting of a single subumboual denticularslight obtuse prominence, which is more distinct in the left than inthe right valve. Ligament small, visible externally, extending onboth cides of the apices of the beaks, but further posteriorly than infront. Height 5^ millim., width -i, length 7f.Hah. West Island, Prince of Wales Channel, Torres Straits( Coppinger).S. liydatina, Deshayes, appears to be more closely related to thisspecies than to any other in the genus. It is, however, higher, moreequilateral, flatter, with more equal sides and a curved ventralmargin.Reeve, Conch. Icon. fig. IG.49. Crassatella pulchra.Hah. Thursday Island, Torres Straits, 3-4 fms. (Oopjnnger) ;Essington {Capt. WicMiam, li.N., in Brit. Mus.).Port