PLATE XX VII I. 



Figs. 1-5. Pachychlcena obesa, Herdmau. 

 Figs. 6-11. PacJiyehlcena gigantea, Herdmau. 



Fig. 1. Pachychlcena obesa, from the dorsal edge and part of the right side ; the greater 

 part of the test has been removed ; natural size. 



Fig. 2. Part of the branchial sac of Pachychlcena ooesa, seen from the interior; magnified 

 (Hartn., obj. 4). 



Fig. 3. Part of the same branchial sac, seen from the exterior; magnified (Hartn., obj. 4). 



Fig. 4. A small portion of the last figure ; more enlarged (Hartn., obj. 5). 



Fig. ">. Part of the dorsal lamina ; magnified (Hartn., obj. 4). 



Fio-. 6. Pachychlcena gigantea, from the left side ; natural size. 



Fig. 7. Part of the branchial sac of Pachychlcena gigantea, seen from the interior; magnified 

 (Hartn., obj. 4). 



Fig. 8. Part of the branchial sac, seen from the exterior, showing the external wide- 

 meshed network, &c. ; magnified (Hartn., obj. 4). 



Fig. i). The interior of the branchial siphon, showing the tentacles and the strong 

 muscular ring ; natural size. 



Fig. 10. The dorsal tubercle, peripharyngeal band, peritubercular area, and tentacles ; 

 slightly enlarged. 



Fig. 11. Part of the dorsal lamina of Pachychlcena gigantea ; very slightly enlarged. 



