BRITISH SPONGIAD^. 93 



softer tissues of the sponge have been more or less con- 

 •tracted by either immersion in spirit or by drying. 



In several living specimens vphich I have obtained im- 

 mediately after they had been taken from the sea, the surface 

 was smooth and not at all hispid, and the terminations of 

 the radial fascicuH of the skeleton which form the wart-like 

 projections in the specimens preserved in spirit or dried, 

 were scarcely visible in the living ones. 



The oscula are not usually visible, but in one specimen 

 of the sponge sent to me by Dr. Battersley, enveloped in 

 wet seaweeds, in a small jar, on immersing it in fresh 

 sea-water, after about an hour I observed several oscula 

 open near the distal end of the sponge ; on probing one of 

 them with a fine grass straw, the whole slowly closed, and 

 I did not again succeed in seeing them open, but this event 

 sufficiently indicated their locality. The diameter of the 

 largest of the open oscula was rather exceeding a Iine< 



The dermal crust of the sponge varies from one to two 

 or two and a half lines in thickness. It appears to be 

 thickest on the upper half of the animal, and especially at 

 the extreme horizontal circumference, and the lower half is 

 frequently not above half the thickness of the upper one. 

 The large subsphero-stellate spicula are abundantly dis- 

 persed in the coriaceous substance of the dermis between 

 the expanding terminations of the distal extremities of the 

 skeleton fasciculi, and the small attenuato-stellate spicula 

 are very abundant on the inner surface of the dermal mem- 

 brane, and immediately beneath it, as if designed to 

 especially protect it from the attacks of small predacious 

 enemies which may have located themselves on its surface. 



The large corymbose expansions of the distal termina- 

 tions of the skeleton fasciculi are produced by the addition 

 of a great number of fusiformi-acuate spicula, not above one 

 thkd or half the size of the proper skeleton spicula ; they 

 are intermingled with the larger ones, without any apparent 

 order, and their distal terminations are in accordance with 

 those of the primary skeleton ones. 



I am indebted to my late friend, Mr. Thomas Howard 

 Stewart, of the Royal College of Surgeons, a promising 



