PLATE XXIII. 



Figs. 1 and 2. Polycarpa rigida, Herdman. 

 Figs. 3-6. Polycarpa lonyisiphonica, Herdman. 

 Figs. 7 and 8. Polycarpa irregularis, Herdman. 

 Figs. 9-13. Polycarpa sulcata, Herdman. 



Fig. 1. Polycarpa rigida, a specimen seen from the left side ; natural size. 



Fig. 2. Part of the branchial sac of Polycarpa rigida, seen from the inside ; magnified 



(Hartn., obj. 4). 

 Fig. 3. Polycarpa longisiphonica, from the left side ; natural size. 

 Fig. 4. Part of the branchial sac of Polycarpa longisiphonica, seen from the inside ; 



magnified (Hartn., obj. 4). 

 Fig. 5. The tip of one of the tentacles of Polycarpa longisip>honica, seen from the side ; 



magnified (Hartn., obj. 5). 

 Fig. 6. The same, seen partly from the front ; magnified (Hartn., obj. 5). 

 Fig. 7. Polycarpa irregularis, a specimen seen from the right side ; natural size. 

 Fig. 8. Part of the branchial sac of Polycarpa in-egtdaris, seen from the inside ; 



magnified (Hartn., obj. 4). 

 Fig. 9. Polycarpa sulcata, a specimen seen from the dorsal surface ; natural size. 

 Fig. 10. Another specimen, seen from the right side ; natural size. 

 Fig. 11. Part of the branchial sac of Polycarpa sulcata, seen from the inside ; magnified 



(Hartn., obj. 4). 

 Fig. 12. A small portion of the last figure, more magnified, and showing muscular fibres 



in the vessels (Hartn., obj. 7). 

 Fig. 13. Part of a section through the test of Polycarpa sulcata, showing the fibrous 



matrix (t.m.), the vessels (v.), and the cavities and terminal knobs (t.k.), 



containing blood corpuscles (Hartn., obj. 7). 



