PLATE X. 



Figs. 1-6. Culeolus icyville-thomsoni, Herdman. 

 Figs. 7-12. Culeolus moseleyi, Herdman. 



Fig. 1. Culeolus wyville-thomsoni, from the left side ; natural size. 



Fig. 2. The branchial aperture ; natural size- 



Fig. 3. The atrial aperture ; natural size. 



Fig. 4. A section through the test, to show the modifications of the blood-vessels ; 

 magnified (Hartn., obj. 4). 



Fig. 5. Part of the branchial sac, from the inside, showing one of the branchial folds (brf.) ; 

 magnified (Hartn., obj. 4). 



Fig. 6. The dorsal region of the anterior end of the branchial sac, showing the inside of 

 the branchial siphon, the tentacles, the prsebranchial zone, the peri- 

 pharyngeal baud, the peritubercular area, the dorsal tubercle, the languets, 

 and part of the branchial sac ; slightly enlarged. 



Fig. 7. Culeolus mosdeyi, from the right side ; natural size. 



Fig. 8. The branchial aperture ; natural size. 



Fig. 9. The atrial aperture ; natural size. 



Fig. 10. Part of the peduncle, showing the brown trabecular ; enlarged. 



Fig. 11. Part of the branchial sac, from the inside, showing one of the branchial folds 

 (br.f.) ; magnified (Hartn., obj. 4). 



Fig. 12. The dorsal tubercle and peritubercular area ; magnified (Hartn., obj. 4). 



