314 



BISCAYAN PLANKTON : THE OSTEACODA. 



Plate 16. 



CoNCHCECiA AMETRA, MiiUer. 



Male. Stage IL Fig. L Shell, 3-0 mm. 



2. Frontal organ, 3'0 mm. 



3. Distal end of armature of principal bristle of antenna i., 3"1 mm. 



4. Pad on proximal accessory bristle of antenna i., 3*2 mm. 



5. Hook-joint and neighbouring structures of inner limb of right 



antenna ii., 3'1 mm. 



6. Hook-joint of left antenna ii., 3'1 mm. 



7. The rostra viewed from inside, 3"0 mm. 

 Stage III. 8. Shell, 2-3 mm. 



9. Frontal organ, and end of antenna i., 2"2 mm. 

 Stage IV. 10. Frontal organ, 1'6 mm. 



11. Inner joint of antenna ii., 1*6 mm. 

 Female. Stage II. 12. Shell, 3-5 mm. 



13. Frontal organ, and end of antenna i., 3"5 mm. 



14. Inner joint of antenna ii., 3"5 mm. 

 Stage III. 15. Shell, 2-3 mm. 



16. Frontal organ, and end of antenna i. (the dorsal bristle not 



shown), 2"3 mm. 



17. Inner joint of antenna ii., 2'3 mm. 

 Stage IV. 18. Shell, 1-5 mm. 



19. Frontal organ, and end of antenna i., 1'5 mm. 



CoNCHCECIA BRACHYASKOS, Miillcr. 



Male. 



Older stage. Fig. 20. Shell, 1-2 mm. 



Younger stage. 

 Female. Older stage. 



Younger stage. 



21. Tooth of armature of antenna i. 



22. Frontal organ, 0'9 mm. 



23. Inner branch of antenna i., 0'9 mm. 



24. Shell, 1-4 mm. 



25. Frontal organ, 1-4. mm. ; antenna i. accidentally displaced. 



26. Inner branch of antenna ii., 1"2 mm. 



27. Shell, 0-8 mm. 



28. Frontal organ, 0"9 mm. 



29. Frontal organ, 0"8 mm. 



