OF THE SPONGIAD^E. 245 



FIG. 



minal curves elevated above the surface of the mem- 

 brane, but always reposing on one side, with all parts 

 of the shaft closely attached to its surface. The three 

 forms figured are from the same specimen of sponge. 

 Page 41. 



99. UNICURVO-CRUCIFORM. X 130 linear. This form 

 occurs abundantly on the membrane lining the 

 great cloacal cavities of Leuconia nivea, Bower- 

 bank. The axial radii are disposed very nearly 

 in the direction of the long axis of those organs, and 

 the curves formed by the lunate radii always have 

 their points towards the mouths of the cloaca. 



100. FALCATO-ACERATK. X 130 linear. This form is 



abundant in a small species of Grantia from 

 Australia, which is found on several species of Fuci 

 in the collections brought home by Dr. Harvey. 

 The sponges do not frequently exceed the eighth of 

 an inch in length. Page 41. 



101. BICURVO-ACERATE. X 260 linear. This form is 



from a small parasitical Grantia from Algoa Bay, 

 in my collection. The sponge is about the size of 

 a large pea, and is not uncommon on Zoophytes 

 from that locality. Page 41. 



102. 103, 104, 105, 106, 107, 108. FOLIATO PELTATE. 



These spicula have the shaft exceedingly short and 

 conical ; the basal termination being acute, and the 

 shaft dilating rapidly to its distal end, to the extent 

 of an angle of about 1 5 or 20 degrees. The apex of 

 the spiculum expands into a large, more or less, 

 circular disc or shield, having in the fully developed 

 state an extremely sinuous or foliated margin ; the 

 plane of the shield or disc being at about right angles 

 to the line of the shaft, and having the under side thickly 

 studded with tubercles, which are separate in the 

 young spicula, and more or less confluent in the fully 

 developed ones. In an early stage of its development 



