453 



Costa Rica Mtocenk — Olsson 281 



Page 



3. Glyc ymeris canalis Brown and Pilsbry, Banana River, about 



natural size 177 



4. Glycymeris canalis Brown and Pilsbry, variety. East Grape 



Point Creek 177 



5. Glycymeris canalis Brown and Pilsbry, variety, East Grape 



Point Creek 177 



6-7. Glycymeris canalis Brown and Pilsbry, Banana River 177 



8. Pecten costaricensis,n. sp.. Red Cliff Creek, right valve 201 



9, Pecten costaricensis, n. sp., Red Cliff Creek, left valve. 



10. Pecten costaricensis, n. sp., Red Cliff Creek, right valve. 



11. Pecten costaricensis, n. sp.. Red Cliff Creek, left valve. 



12. Leda ensinoides, n. sp., Banana River, length 54 mm 174 



13. Glycymeris castaneus Lamarck, Banana River, length 30 mm. 180 



14. Glycymeris castaneus Lamarck, Banana River, length 23 mm. 



15. Leda Balbose Brown and Pilsbry, Banana River, enlarged 173 



16. Pecten almirantensis, n. sp, , Bocas del Toro,heigth 4.75 mm. 203 



17. Pecten aotus, n. sp., Port Limon, height 4.50 mm 204 



18. Pecten aotus, n. sp., Port Limon, 4.75 mm. 



19. Leda quitanensis, n. sp. , Quitana Creek, length 26 mm 174 



20. Leda Davilse, n. sp., Bocas del Toro, length 5.75 mm 173 



21-22-23-24. Nucula cahuitensis, n. sp., Saury, length 3.50 mm 171 



25. Nucula tenuisculpta Gabb, Red Cliff Creek, length 4.00 mm. 172 



PLATK 19 (22) 



Fig. I. Glycymeris carbasina Brown and Pilsbry, East Grape Point 



Creek, about natural size 179 



2. Glycymeris carbasina Brown and Pilsbry, same locality, 



about natural size 179 



3-4. Glycymeris jamaicensis. Red Cliff Creek, about natural size 178 



5. Glycymeris carbasina Brown and Pilsbry, East Grape Point 



Creek, small shell about natural 

 size 179 



6-7. Glycymeris decussatus Lamarck, Old Man Sam Creek, nat- 

 ural size 180 



PLATE 20 (23) 



Fig. 1. Spondylus chiriquiensis, n. sp., Water Cay, height 151 mm... 206 



2, Spondylus chiriquiensis, n. sp., young shell to show the small 



foliaceous attachment area. 



3. Thracia Tristani, n. sp., Rio Betey, length 42 mm 211 



