91 



Plate XXXVI. 



HYMENIACIDON SUBEKEA, Bower bunk. 



Vol. ii, p. 200, 'Mon. Brit. Spongiadse.' 



Fig. 1. Represents a specimen of the sponge from 

 Shetland, dredged in about 70 fathoms. The shell, 

 about one inch and a half in length, is entirely en- 

 veloped by the sponge. Natural size. 



Fig. 2. A fully-developed skeleton spiculum. 

 X 150 linear. 



Fig. 3. A smaller and less developed skeleton 

 spiculum. X 150 linear. Every variety in size may 

 be seen between the spicula represented by figs. 2 

 and 3. 



Fig. 4. Represents a very slender and early stage 

 of development of a skeleton spiculum in which the 

 spinulate base is doubled. Numerous other abnormal 

 productions of the spinulate base are of frequent oc- 

 currence in the young and immature spicula of this 

 species. 



HYMENIACIDON CARNOSA, BowerdanL 



Vol. ii, p. 203, ' Mon. Brit. Spongiadse.' 



Fig. 5. Represents the specimen from Plymouth 

 presented to me by Mr. J. H. Stewart. There are four 

 specimens of the sponge on the Pecten shell, two 

 comparatively large and two very young ones on 

 the grooves of the shell opposite (a). There is no 

 indication of pedestals to either of the four specimens. 

 Natural size. 



Fig. 6. A specimen from Strangford Lough, Ireland, 

 on a dead shell of cerithium elevated on a contorted 

 pedestal, the base of which embraces about two thirds 

 of the circumference of the shell. Natural size. 



Fig. 7. A specimen from Orkney Islands, pre- 

 sented to me by Mr. McAndrew. This specimen has 



