VELUTINA. 241 



deeply indented and narrowed on each side, and rounded or 

 bluntly pointed behind when at rest ; it occupies nearly all 

 the aperture of the shell ; when extended, the sole is shaped 

 like a shoe : [gills arranged in two plumes, which are unequal 

 in size (Clark) :] male organ falciform, short and yellow, issu- 

 ing on the right-hand side of the head. 



Shell triangularly oval, not so thin as the last species, semi- 

 transparent, lustreless except when the epidermis has been 

 removed, or (as is sometimes the case) has failed to grow : 

 sculpture, conspicuous and regular, but slight, spiral ridges, 

 and numerous minute longitudinal striae, which cross the ridges 

 in the early stages of growth ; there are also the usual lines 

 of increase : colour whity-brown, tinged with fleshcolour or 

 pink (especially in southern specimens) : epidermis tough, 

 yellowish-brown, folded on the ridges of the shell, and longi- 

 tudinally fibrous: spire twisted upwards: ivliorls 34, ventri- 

 cose, the last occupying nearly the whole of the shell and ex- 

 panding outwards : suture deeply channelled, so as to expose 

 a considerable portion of the penultimate whorl : mouth 

 roundish -oval, dilated, placed a little below the periphery, and 

 equalling in length seven-eighths of the shell, slightly angu- 

 lar above and rounded below ; inside white, pale orange, or 

 fleshcolour : outer lip forming almost an arc of a circle ; the 

 edge, being thin and covered by the epidermis, shrinks when 

 the shell is dried, and is usually broken or cracked : inner lip 

 lying at a lower level than the other, flexuous, and mostly 

 white, broadly reflected on the upper part of the pillar (where 

 it joins the outer lip), having elsewhere a thick edge ; behind 

 it is a slight umbilical depression or chink. L. 0*8. B. 0-7. 



Yar. Candida. White. 



Habitat : Everywhere beyond tide-marks, on hard 

 ground. The variety occurred to me on the coasts of 

 Antrim, the Hebrides, and Shetland. Fossil in the 

 Clyde beds (Smith and others) ; Mammalian Crag at 

 Thorpe (S. Wood); post-glacial deposits at Uddevalla 

 (J. G. J.), and in Norway, 30-120 feet (Sars). Inha- 

 biting the North Atlantic, from Greenland, Spitsbergen, 

 Lapland, and Kamptschatka to Vigo (M'Andrew) and 

 Spezzia (J. G. J.), with a range from low-water mark 



VOL. IV. M 



