PUNCTURELLA. 257 



Emarginula as Schismope does to Scissurella. Other 

 synonyms of Puncturella are Diodora, Gray (according 

 to De Blainville) _, and Sipho, Brown. 



tv jLira. PUNCTURELLA NOACHI'NA *,(Linne.) H- "9 



Patella Noachina, Linn. Mant. Plant, p. 551. Puncturella Noachina, 

 F. & H. ii. p. 474, pi. bdi. f. 10-12, and (animal) pi. B B. f. 4-6. 



BODY milk-white with a faint tinge of brown : mantle thick ; 

 tubular fold conical and short, furnished with six small papilla 

 in front and four behind : head large and broad, bilobed : 

 tentacles conical and pointed, rather short, greatly diverging, 

 and ciliated : eyes large and prominent : foot oval, broader and 

 somewhat truncated in front, bluntly pointed behind ; upper 

 side forming a ridge, which is studded with short white conical 

 points (ten on each side) corresponding with the ribs of the 

 shell ; those in front, especially the penultimate ones near the 

 tail, are larger than the rest. 



SHELL more or less raised, slightly compressed at the sides, 

 rather thin, semitransparent, not glossy: sculpture, 25-30 

 sharpish but not much elevated ribs, which radiate from the 

 beak to the margin, and as many smaller intermediate ones ; 

 the surface is also covered with microscopical and close-set 

 longitudinal striaB, and with minute white and glistening dots, 

 which are arranged lengthwise in rows, and seem to indicate 

 an internal tubular structure ; lines of growth slight and 

 irregular : colour whitish : beak small, ribless, incurved, and 

 twisted to the left, forming a spire of one whorl and a half: 

 slit lanceolate, extending from the crown some distance down 

 the front, and passing obliquely in that direction : mouth oval, 

 somewhat broader behind : margin thin, scalloped or indented 

 by the ribs : inside nacreous, marked with fine concentric 

 lines; from the centre or crown towards the front runs a 

 rather large vaulted sheath, occupying more than one-fourth 

 of that side ; it covers the slit, which is continued in front of 

 the sheath in the form of a narrow groove with thickened 

 sides, nearly to the margin ; the sheath is strengthened at 

 each side by a rather solid buttress. L. 0-4. B. 0-3. 



Var. princeps. Shell higher and much narrower from being 

 pinched up at the sides, with the mouth consequently oblong. 

 Cemoria princeps, Mighels and Adams. 



* So named (as a fossil) from its supposed diluvian origin. 



