PATELLA. 237 



scopically fretted in the last mentioned part ; margin bevelled : 

 annular scar broad : central scar of every colour from white to 

 dark brown. L. 1-75. B. 1*5. 



Var. 1. elevata. Shell much smaller, rounder, and higher. 



Yar. 2. picta. Shell smaller and thinner; with alternate 

 rays of reddish and dark blue. 



Yar. 3. intermedia. "Animal black or dark-coloured" 

 (Knapp). Shell rather smaller, natter, and oval, with finer 

 ribs, and an orange crown ; inside golden-yellow, or tinged 

 with neshcolour (occasionally creamcolour) in the centre, and 

 beautifully rayed towards the margin. 



Yar. 4. depressa. Body creamcolour ; mantle fringed with 

 yellowish- white or pale drab cirri ; foot light oraugecolour. 

 Shell usually much depressed., and more oblong than the ordi- 

 nary form ; ribs finer but sharp ; beak nearer to the anterior 

 end; inside porcellanous, with a pale orange head-scar or 

 spatula. P. depressa, Pennant, Brit. Zool. iv. p. 142, tab. 

 lxxxix. f. 146 (not P. depressa of Gmelin) ; P. athletica, F. & H. 

 ii. p. 425, pi. lxi. f. 7, 8. 



Yar. 5. ca'mdea. Shell depressed, roundish-oval; ribs 

 more delicate, and less regular : inside dark blue. P. ccerulea, 

 Linne, S. N. p. 1259. 



Habitat : Between tide-marks, on rocks and stones, 

 everywhere, most plentiful. The first variety occurs 

 in North Devon, the opposite coasts of South Wales, and 

 at Sark. The second is not uncommon in the Channel 

 Isles. The third is also from the Channel Isles, where 

 the late Dr. Knapp first noticed it ; and Mr. J. D. 

 Humphreys found it at Cork. The fourth frequents 

 rocks onlv at low water : it is the P. Tarentina of 

 Lamarck, P. Bonnardi of Payraudeau, and P. athletica 

 of Bean. It is in most cases easy to separate this from 

 the ordinary form ; but the variety intermedia connects 

 the two, and I cannot find a single permanent character 

 which will serve to distinguish any of them. The colour 

 of the animal is of every hue and shade ; nor is the 

 shell less variable, taking into account the shape, height, 



