102 LITTORINID.E. 



solid chocolate coloured variety, which has the exact shape 

 of the typical parva^ but is quite destitute of ribs. The 

 individual itself is smooth, but obsolete spiral lines are 

 wont to appear on the neighbouring variety fasciata, in 

 which the coloured zones being continuous, the shell re- 

 minds one of cimi'iUus. 



Plate LXXVI. fig. 2, represents the R. dhcrepans of 

 Brown (Jllustr. Oonch. G. B. p. 13, pi. q, f. 70, 71) which 

 we take to be rather a monstrosity than a distinct variety. 

 The whorls are looser and more rounded than usual, and 

 here and there one of them, at random, displays an 

 isolated series of longitudinal ribs. 



The animal is yellowish-white except the mouth and 

 summit of the head, which are often, but not always, 

 orange-tawny, sometimes inclining to dark purple, and 

 the lateral lobes, which are similarly tinged. The tenta- 

 cula are white, long, and setaceous, with eyes conspicuous 

 on their outer bulyino- bases. The lateral lobes are 

 large and conspicuous. The foot is shorter than the 

 body whorl, narrow, slightly squared in front, pointed 

 behind. On the caudal extremity is an operculigertuis 

 lobe, furnished posteriorly with a prominent white tail 

 filament. 



The form imrxia is abundant all around our shores ; 

 plentiful everywhere dead in shell-sand, and living under 

 stones and among corallines near lovv-water-mark. Hence it 

 ranges in great quantity throughout the Laminarian region. 

 We have dredged it alive in twelve fathoms, Weymouth, 

 and twenty fathoms ofi' Penzance, and Mr. M 'Andrew has 

 taken dead specimens in from forty-five to fifty-five 

 fathoms water oif Cape AVrath and the Zetland Isles. 

 Lieut. Thomas remarks that it occurs clustered in im- 

 mense numbers on the branches of Corall'ma officinalis^ in 



