24 LITTORINID/E. 



a strong magnifying power : eyes on short stalks, occasionally 

 nearly sessile : foot squarish or slightly rounded in front, con- 

 tracted in the middle, where it is apparently divided across 

 into two unequal portions (the front being about half the size 

 of the other portion) ; it tapers behind to a blunt point ; sole 

 speckled with frosted white, and finely slit from the centre 

 down to the tail : opercular lobe large, dark-purple : appendage 

 cylindrical, slender, rather long, and whitish, placed over the 

 tail or hinder part of the foot, and now and then projecting 

 beyond it ; it is microscopically cihated, and resembles a small 

 auxiliary tentacle. 



Shell conic-oval, rather solid, nearly opaque, somewhat 

 glossy: sculpture, strong and shghtly curved ribs, like but- 

 tresses, of which there are 8 on the body- whorl, and 12 on 

 the penultimate and next whorl (the succeeding whorls having 

 no ribs) ; the ribs do not extend to the base ; their interstices 

 are frequently cancellated, and their termination on the lower 

 part of the last whorl defined by more or less distinct spiral 

 striae, arising from the intensity or concentration of micro- 

 scopical lines which cover the whole surface in that direction ; 

 the labial rib is thick and white, placed at a short distance 

 behind the outer lip : co/oitr mostly pale yellowish-white, some- 

 times brown or chocolate, obscurely marked occasionally with 

 rays between some of the ribs, and mth a band round the 

 base, always having a falciform streak from the suture behind 

 the labial rib towards the middle of the outer lip ; the rays, 

 band, and streak are chestnut-brown ; sometimes the ribs are 

 white, the tip is pinkish, and the mouth is edged with chest- 

 nut-brown : spire short, bluntly pointed : ivhorls 6-7, convex, 

 the last occupying nearly two-thirds of the spire : suture rather 

 slight, but distinct: mouth roundish- oval, somewhat expanded : 

 outer lip thin, contracted and incurved above: inner lip reflected 

 on the pillar and at the base, where there is no appearance of 

 an umbilical crevice : operculum thin, whitish, with a small 

 excentric spire, and delicately striated. L. 0-165. B. 0-1. 



Yar. 1. interrupta. Smaller, slenderer, thinner, semitranspa- 

 rent, and ribless, with much less convex whorls, usually marked 

 with longitudinal rays of chestnut-colour, which are curved on 

 the body-whorl, or di^4ded into two rows, so as to make the mid- 

 dle appear girdled with a whitish band ; occasionally these rays 

 become confluent and form dark bands ; labial rib slighter ; the 

 spiral striae are sometimes distinct, although irregular. Turbo 

 interruptus, Adams in Tr. Linn. Soc. v. p. 3, t. i. f. 16, 1 7. 



