254 PATELLID.E. 



having a distinctly spiral apex and a plate or septum 

 inside the crown. The use of this last-mentioned pro- 

 cess is not known. It is too small to contain or support 

 the viscera^ as in Calyptraa and allied genera ; but it 

 may be homologous with the internal process of Punc- 

 ture lla. 



Propilidium ancyloi'de ^j Forbes. 



Patella ? Ancyloides, Forbes, in Ann. Nat. Hist. v. p. 108, pi. ii. f. 16. 

 Propilidium Ancyloide, F. & H. ii. p. 443, pi. ixii. f. 3, 5, and (animal) 

 pi. A A. f. 4. 



Body whitish with a faint tinge of yellow : mantle fringed 

 at its edge with close-set but distinct cilia, which correspond 

 with the striai of the shell : head semicircular, margined with 

 light brown : mantle scalloped or puckered : tentacles tapering 

 to a fine point, delicately ciliated, destitute of eye-stalks : 

 foot oval, broader in front than behind. 



Shell having an oval outline, compressed at the sides, 

 rather thin, semitransparent, glossy at the apex, but else- 

 where of a dull hue : sculpture, very numerous and close-set 

 fine striae, which radiate from the beak and are exquisitely 

 granulated in consequence of their being intersected or decus- 

 sated by equal-sized concentric stria3 : colour dirty white, 

 occasionally diversified by a few clear longitudinal rays or 

 lines : beah smooth and highly pohshed, styhform and slender, 

 pinched up into a minute spire of between one and two whorls, 

 which curls downwards at the posterior end : mouth oval, of 

 nearly the same breadth throughout : margin thin and even, 

 minutely tuberculated in immature specimens: inside nacreous, 

 furnished in the centre with a thin laminar partition, like the 

 half deck of a vessel, which has its opening towards the 

 head or anterior part; pallial scar broad. L. 0-15. B. 0-115. 



Habitat : Not uncommon on stones and among 

 nullipores, in co. Galway (Barlee); Stra igford Lough on 

 oysters, and on the Antrim Coast in 18-100 f. (Hynd- 

 man and others) ; Ballantrae, Ayrshire (Getty) ; Lam- 

 lash Bay (Smith, Forbes, and others) Oban, 20 f. 



* Having the aspect of an Ancyl . 



