PLATE XV. 39 



preserved in spirit as it came from the sea. Natural 

 size. 



This specimen is based on the remains of a fucus, 

 and partially so to a small pebble on one side of it. 



In consequence of their immersion in spirit the 

 corymbose terminations of the skeleton fasciculi are 

 distinctly visible in both specimens, but they are not 

 projected beyond the surface as it is usual in dried 

 specimens. 



Fig. 19. --One of the fusiformi-acuate skeleton 

 spicula. X 80 linear. 



Fig. 20. One of the slender, fusiformi-acerate, ten- 

 sion spicula of the interstitial membranes. X 80 

 linear. 



Fig. 21. A large, sub-sphero-stellate spiculum, 

 with acutely conical radii from the derinis. X 320 

 linear. 



Fig. 22. One of the minute, cylindro- stellate, reten- 

 tive spicula from the inner surface of the dermal mem- 

 brane. X 320 linear. A large number of these 

 spicula have the radii more or less acutely termi- 

 nated. 



In vol. i, plate xxv, fig. 342, ' Mou. Brit. SpongiadaB,' 

 there is figured one of the external gemmules of this 

 species from the base of a specimen found at Plymouth 

 by my late friend Mr. Thomas Howard Stewart. 

 X 50 linear. 



Mr. Peach has also found this species in Fowey 

 Harbour. 



TETHEA SPINULARIA, Bowerban/>\ 



Vol. ii, p. 94, ' Mon. Brit. Spongiadse.' 



Fig. 23. Represents the largest specimen of this 

 species that I have yet seen. It was dredged at 

 Shetland by the Rev. A. M. Norman, in whose pos- 

 session it remains. It was relaxed in salt water pre- 

 viously to being figured. Thirteen distinct mammil- 



