112 
pellucid, corneous, about eighteen radiating ribs running 
the entire length of the shell; ventral edge rounded. 
23...6. 8. Coasts. Towards the middle posteriorly, 
the scaly strie run obliquely to the margin. 
* PP. PapyRacEA. Turt. B. p. 224. t. 20. f. 3.—F. 
p. 407.—Oval triangular, thin, brittle, with nine dis- 
tant unarmed ribs nearly covering the entire surface ; 
ventral edge slightly rounded ; contracted rapidly to- 
wards the apex ; the open end even. 24...43. Devon. 
Tripe.—-MALLEACEA. Lam. 
Subinequivalve, foliaceous, ligament marginal ; sub- 
linear ecther entirely simple or interrupted by cre- 
nulations or a row of teeth. 
Grenus.—_CRENATULA. 
Subequivalve, flattened, foliaceous, somewhat irregular, 
no particular aperture for the byssus ; hinge lateral, 
linear, marginal, crenulated ; crenations arranged 
ina straight line, callous, somewhat excavated, re- 
cewing the ligament. 
C. Travis. Turton in Mag. N. H. 7. p. 349. f. 
* Muricata, fide Turton, is probably not native. 
