80 



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



— Hi. 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. Tlie 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. 



Fig. 24—32. Fungiacyathus i'ragilis. 



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^'' 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. 



'^Pl. VI. 

 Fig. 1 — 15. Ti'ichostemina hemisphfericum. 



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 smifice, strongly mag- 



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



