80 



Fig. 15. A calcareous joint, with a lateral process in the middle (rudiment of a lateral branch). 



16. An unusually short and thick calcareous joint. 



17. An other likewise unusually thick but more elongated and somewhat twisted cal- 

 careous joint. 



18. The root of an unusually large colony; side view. 



19. The same, seen from above. 



20. A single root-blade greatly enlarged at the extremity, seen from the outer side. 



21. The same, from the inner side. 



22. The lower part of a colony, with abnormally developed root, seen from the side. 



23. The same, seen from above. 



Fig. 2432. Fungiacyatlms fragilis. 



Fig. 24. A specimen with the animal seen from above, not quite twice the natural size. 

 The ciphers indicate the different orders of septa. 



25. The same, seen from below. 



26. An other specimen with more enlarged bucal aperture. 

 27. The same, seen from below. 



28. One of the inner tentacles, with a piece of the skin investing the corresponding 



primary septum, more strongly magnified. 



29. The skeleton of a 3 r . d specimen, seen from the side, shewing the high thin septa. 

 1. 2. 3 the primary, secundary, and tertiary septa. 



30. The same specimen seen from above. 1 the primary septa. 



31. One of the primary septa, seen from above. 



32. The same, seen from the side. 



PI. VI. 



Fig. 115. Trichostemma hemispluericum. 



Fig. 1. The largest specimen found, seen from above, natural size. 

 2. The same specimen, seen from the side. 



3. One of the smallest specimens obtained, with only a single osculum, seen from above. 



4. An other specimen, cut through the middle, shewing the interior parenchymatous 

 cavity and the exterior cortical stratum, with 2 of the fistular oscula in section. 



5. A thin lamella, cut out of the sponge perpendicularly to the surface, strongly mag- 

 nified, shewing the arrangement of the spicula. a-c the cortical stratum ; a-b the 

 dermal layer of the same; c-d, the interior parenchym. 



6. Pin-shaped (fusiformi-spinulate) spicula from the cortical stratum, a, the ordinary 

 form; 6, a very thin spiculum, which however still shews the fusiformi-spinulate shape ; 

 c, one of the spicula which are closely packed in the dermal layer; d, the head and 

 base of the shaft of a somewhat abnormal spiculum of the same sort. 



