262 . PATELLID^E. 



when compared with the commoner appearance of its con- 

 gener. The two species inhabit generally different levels, the 

 P. vulgata occupying the higher one. This species is partially 

 distributed ; it is found tolerably plentiful in an area of half 

 a dozen acres near Exmouth, very few of the P. vulgata being 

 in company in its own level ; but these are congregated in 

 great numbers in the higher levels, with the P. athletica rarely 

 amongst them. The great distinguishing character of the 

 two is the fringe of the mantle, which in the athletica is snow- 

 white, but in its congener a pale uniform drab ; it also varies 

 in length and thickness ; a comparison of them in sea-water 

 will at once impress a conviction that they are specifically 

 distinct. 



ACM^EA, Eschscholtz. 



A. VIRGINEA, Miiller. 



A. virginea, Brit. Moll. ii. p. 437, pi. 61. f. 1, 2. 

 Patella virginea, Auctorum. 



Animal oblong-oval, pale yellow, inhabiting a subconical 

 patelloid shell marked with shallow radiating lines, and minute, 

 pink, narrow longitudinal fasciae; vertex anterior; mantle 

 even with the shell, bordered with a rather long fimbriated 

 fringe, inflected gently inwards; it is interspersed with red 

 patches and pink lines to correspond with those on the test. 

 Head dull pale orange, sometimes rose-colour, issuing from 

 the end to which the apex curves ; it appears very short by 

 being separated from the neck by a conspicuous circular white 

 veil, or rather pavilion, with a pendent oval flap or lappet on 

 each side ; the neck is pale rose ; the buccal disk has a ver- 

 tical fissure, within which are two pointed, linear, greenish 

 corneous plates supporting the palate, through which a long, 

 red-brown, narrow lingual riband passes to the oesophagus 

 and stomach. The tentacula are long, white, setose, eminently 

 contractile, tumid at the bases, conically tapering to a fine 

 point, with eyes on very short pedicles, at their external bases. 

 The foot in extension is an elongated oval, plain-edged, white 

 on both surfaces, quite plain, and destitute of papillae or 

 ornament around the strong fleshy pedicle. The arcuated 



