162 TJTTORINID.E. 



prefcrrerl to adopt the name of the universally recognised 

 and clearly defined species of Dr. Fleming. 



This shell is of an uniform pure white, and of a some- 

 what oblique depressed-orbicular shape. It is, perhaps, 

 less thin, glossy, and transparent than most of the species 

 we have provisionally grouped it with. It is composed of 

 barely three whorls, which most rapidly enlarge in size, 

 are simply convex, and are divided by a profoundly im- 

 pressed, but not canaliculated suture. The spire is scarcely 

 elevated, the penult turn being depressed, and the apex 

 short though rather prominent. The body is cylindrical, 

 but rather more rounded below than above ; its periphery 

 is not at all angulated, biit rather broadly rounded. Cos- 

 tellar stria) encircle the base, and enter the capacious 

 mouth of the umbilical cavity ; upon the middle of the 

 whorl the}'' are replaced by closely disposed and simply 

 impressed striae, and wholly or partially disappear upon 

 the upper disk. Owing to the somewhat loose nature of 



* The S. Serpuloides of that writer (Brit. Anim. p. 314, copied in Brit. Marine 

 Conch, p. 158) presents a peculiar feature which we have not seen, unaccompanied 

 by spiral lines, in <iny widely-umbilicated British Skenca. 



" Whorls three, white, smooth, glossy, subopaque, round, nearly on a level 

 above, with a deep separating line ; beneath, with a central cavity, round which 

 tliere are traces, under a Jiir/h magnifier, of diverging lines of gro^vt^l ; aperture 

 circular, with the margin little reflected. Breadth about a tenth of an inch. Not 

 uncommon from deep water." 



Turton, in his " Manual of Land and Freshwater Species," has erroneously 

 cited for his Valvata minuia (p. 132, f. 117) the H. Serpxtloides of Montagu and 

 of his own " Dictionary." In this he is not consistent, for in the first-mentioned 

 work of his he limits the number of the whorls to two, or two and a half at the 

 utmost, though in his earlier publication he had thus described it : — 



"■ Shell flat, white, glossy, smooth ; spires three or four, nearly flat and level 

 on both sides, the upper surface being very slightly raised ; the under side with 

 a large and deep perforation, exposing the interior volutions ; aperture orbicular, 

 slightly adhering to but not clasping the body volution, tlie margin not very thin ; 

 diameter the tenth of an inch. Western coasts ; and in Dublin Bay we have 

 found them double the size." We found no specimens in Turton's cabinet wliicli 

 agreed correctly with this description. 



