280 MR. CONRAD'S DESCRIPTIONS OF FRESH WATER AND MARINE SHELLS. 



TRITON. 



T. PERFORATus. PI. 39, fig. 6. — Subpyriform ; volutions five or six; ribs revolving, flattened, slightly 

 prominent, wide and narrow alternately, with narrow interstices and an occasional revolving line ; 

 angle of body whorl tuberculated ; spire scalariform, the angle of each whorl with a tuberculated rib 

 or carina ; color cinereus ; epidermis brown, rough, hairy, longitudinally ribbed ; aperture wide ; 

 margin of labrum sinuous above, profoundly ribbed ; ribs about half an inch long, on an ochraceous 

 submargin ; columella with white folds, and narrow, dark brown interstices ; beak bent, umbilicated. 



OLIVA. 



0. PROPATULA. PI. 39, fig. 7. — Ovate-oblong, slightly gibbous towards the base ; color pale ochraceous, 

 marked with a few longitudinal zigzag brown lines, and with darker transverse hair-like lines, and a 

 few spots ; columella patulous, deeply sulcated inferiorly ; deposit at the base carinated in the middle. 



REFERENCE TO PLATE XXXVII. 



Fig. 1. 



Unio securiformis. 



2. 



stagnalis. 



3,4. 



Ogeecheensis. 



5. 



rosaceus. 



Fig. 6. 



Unio oratus. 



contrarius. 



nucleopsis. 



limatulus. 



REFERENCE TO PLATE XXXVIIL 



Fig. 1. 



Melania sublirata. 



2. 



Unio perplicatus. 



3. 



Melania cselatura. 



4. 



Unio nodiferus. 



5. 



Melania symmetrica. 



6. 



perangulata. 



Fig. 7. Unio plectophorus. 



8, nodiferus. 



9, Melania nebulosa. 



10. percarinata. 



11. Unio Mississippiensis. 



Fig. 1. 

 2. 

 3. 

 4. 

 5. 

 6. 



Solecardia eburnea. 

 Petricola sinuosa. 

 Pholadopsis pectinata 

 Parapholas bisulcata. 

 Penitella Wilsonii. 

 Triton perforatus. 



REFERENCE TO PLATE XXXIX 



Fis:. 7 



Oliva propatula. 



8. Donax protracta. p. 208. 



9. Venus intapurpurea. 209. 



10. Pecten fuscopurpureus. ib. 



11. P fragosus, 214. 



