DESCRIPTION. 
133 
Fig. 4. O. Folium. 
Shell ovate, obtusely plaited at the sides, para- 
sitical. 
jy Argenmlle Conch. Tab. 19. F. 
Specimen pale purplish brown, underneath in- 
clining to white ; hinge with a triangular sinus ; 
upper valve turgid towards the middle, rough and 
transversely ribbed on both sides ; lower valve 
smaller, flat, and channelled through the middle. 
Inhabits the Indian Ocean. 
Fig. 5. O. isogonum. 
Shell equivalve, lobed, the larger lobe at right 
angles to the hinge. 
Humph. Mus. Tab. 47. I. 
Specimen inclining to violet, with shades of 
black, within pearly ; lamellate; beak unclosed. 
Inhabits the Indian Ocean and South Seas. 
♦ 
PLATE X. 
Fig. 1. Anomia vitrea. 
Shell nearly orbicular, ventricose, hyaline, ex- 
tremely thin ; lower valve with two bony rays at 
