20 
B. Atcrontt.—Lepas A. Turt. D. p. 76.—Some- 
what conic, white or brownish white, with six very 
unequal and irregularly sized valves which terminate 
in rather acute points; aperture large, oval or roundish, 
lid of four valves, the two uppermost smooth, pointed, 
gaping a little at top and protuding in the middle into 
a kind of keel. Diameter and height $. On Alecy- 
onium and Flustra, Weymouth. 
GrENnus ACASTA. 
Sessile, oval, subconical, composed of separable pieces, 
valves siz, laterally united, unequal; the basis an 
orbicular, internally concave, testaceous lamella ; 
operculum quadrivalve. 
A. Montacut. Leach. Cirrhip.—Lam. 1.—Baua- 
Nus Sponeeosus. Mont. Sup. p. 2. t. 7. f. 4, 5, 6.— 
Bl. t. 85. f. 3.—Dor. Cat. p. 25.—Lepas 8S. Turt. 
D.p. 78.—D. p. 27.—Wood. G. C. p. 47.—Livid 
brown with a purple tinge towards the summit; valves 
six, wrinkled, sharply pointed, the three anterior the 
broader and shorter; opereulum quadrivalve, the two 
anterior pieces rough with decussated striae, the two 
posterior longer and a little hooked forwards. }. 
Portland Reach; in sponge, rare. 
Genus PYRGOMA. 
Sessile, univalve, subglobular, ventricose, convex above, 
