MOIXTTSCA. 107 • 



given by Quoy and Gaimard of their Psam/mobia vitrea and with the 

 figure in Mobius's work above referred to, pi. xxi. figs. 10 a, 6. The 



foot protrudes at the narrower end of the shell; it is small when 

 retracted, of a boot-like form, roundly carinate at the base, pointed 

 at the tip, and furnished with what is probably a byesiferous process 

 at tho posterior end (" talon," ',>. & (J.) : this is of an opaque white 

 colour. The mantle is opon in front and the anterior half of the 

 ventral margin for the passage of the foot, and united along the 

 rest of the basal and hinder margins, whore there is a minute 

 siphonal perforation. The surface of the mantle beneath is covered 

 with papillae, and the membranous marginal expansion in life pro- 

 bably covers nearly the entire surface of the shell, for even in spirit 

 specimens it still extends halfway up the valves. There are two 

 labial palpi on each side. From this description the close relation- 

 ship with Qaleomma is very apparent. 



The dentition of this species, according to my observation, does 

 not agree with the description given by Deshayes. In the right 

 valve I find a prominent tooth a little in front of the beak, and a 

 second more remote behind it ; the left valve has two teeth, of 

 which the anterior is the smaller, just beneath the umbo, and a 

 third a little behind it. The ligament is externally visible, being 

 attached to the hinge-line above the teeth, a portion of it being 

 internal above and between the teoth. 



48. Scintilla alberti. (Plate YII. figs. G, G 1.) 



Shell small, pellucid, milky white, considerably inequilateral, 

 transversely oblong, shorter and narrower in front of the umbones 

 than behind them, moderately swollen. Lateral and dorsal mar- 

 gins curved, ventral rather rectilinear. Surface glossy, exhibiting 

 (under the lens) distinct concentric lines of growth and also minute 

 radiating and somewhat interrupted stria), visible only under a 

 compound microscope. Umbones small, slightly elevated above the 

 hinge-margin, not quite adjacent, the valves being closed. Cardinal 

 teeth insignificant, consisting of a single subumbonal denticular 

 slight obtuse prominence, which is more distinct in the left than in 

 the right valve. Ligament small, visible externally, extending on 

 both sides of the apices of the beaks, but further posteriorly than in 

 front. Height 5-| millim., width 1, length 7-t. 



Hah. West Island, Prince of Wales Channel, Torres Straits 

 (Coppinger). 



S. hydatina, Deshayes, appears to be more closely related to this 

 species than to any other in the genus. It is, however, higher, more 

 equilateral, flatter, with more equal sides and a curved ventral 

 margin. 



49. Crassatella pulchra. 



Reeve, Conch. Icon. fig. 16. 



Hah. Thursday Island, Torres Straits, 3-4 fms. {Coppinger) ; Port 

 Essington (Capt. Wiclham, B.N., in Brit. Mus.). 



