252 AVICULACE^. 



Avicula Tarentina, Lam. Anim. s. Vert. (ed. Desh.) vol. vii. p. 99. — Brit. Mar. 

 Conch, f. 109. — Desh. Encyclop6d. Method. Vers. vol. ii. 

 p. 99. — Philippi, Moll. Sicil. vol. i. p. 76, and vol. ii. p. 

 55. — Hanl. Recent Shells, vol. i. p. 262.— Desh. Exp. 

 Scient. Algerie, Moll. pi. 129, 

 „ falcata. Lam. Anim. s. Vert. (ed. Desh.) vol. vii. p. 98 {Me Desh.) 

 „ aculeata, Sowerby, Genera Shells, Avicula (from Madeira), f. 2 (proba- 

 bly). — Reeve, Conch. Systemat. pi. 109, f. 2 (from last). 

 „ Anglica, Brown, Illust. Conch. G. B. p. 74, pi. 23, f. 3. 

 „ Ailantica, Brown, 111. Conch. G. B. p. 74, pi. 46, f. 7 (from Turton's 

 figure). 

 Encyclopedie Methodique, Vers, pi. 177, f. 8. 



It is difficult to find any object to wliicli we may liken 

 the shape of this graceful bivalve ; some individuals, how- 

 ever, whose wing is peculiarly elongated, have a contour 

 like that of a falchion. Perhaps the image of a mussel 

 placed in an oblique position, with a small subtriangular 

 lobe on one side of its apex and an elongated wing- 

 shaped appendage on the other, would convey as near 

 an ideal of its shape, as can be approached by lan- 

 guage. The shell is thin and extremely fragile, mode- 

 rately convex, and with more or less of a resinous gloss. 

 The colour is of a pale olivaceous yellow, with more or 

 less distinct and numerous rays or blotches of a smoky 

 brown ; sometimes there are clusters of zigzag streaks, 

 or even long and uninterrupted rectilinear ones, but their 

 arrangement is invariably radiating. The surface which 

 is usually smooth upon the umbones, is elsewhere either 

 marked with somewhat remote concentric strise, or covered 

 towards the margin with rather distant foliaceous subim- 

 bricated laminee. These, in the finer examples, are closely 

 set with ajipressed and somewhat spinous scales, which, 

 however, are almost invariably abraded in the old, and 

 not yet developed in the young, exhibiting only more 

 or less faint indications of a foliaceous structure. The 



