OF THE SPONGIADjB. 55 



tylocalyx pumicea, Stutchbury, Iphiteon of the French 

 Museum. In general character they are very similar to 

 those of the Alcyoncellum described above, with the addition 

 of the apices of the radii being more or less elevated. 



All the simple rectangulated hexradiate forms of spicula 

 hitherto described are large compared with the rectan- 

 gulated hexradiate spicula which form the central bases of 

 the compound stellate forms, and excepting the disparity 

 in size, the transition from the last form described, to the 

 complicated and beautiful compound stellate ones, is easy 

 and natural ; the apices of the hexradiate form becoming 

 the bases of the numerous radii of the stellate ones. This 

 transition from the simple to the compound forms is 

 admirably illustrated in a bifurcated spiculum that occurs 

 in the new species of Alcyoncellum in the Museum of the 

 Jardin des Plantes. This form I have designated bifurcated 

 rectangulated hexradiate stellate, represented by Fig. 188, 

 Plate VIII. The next stage of development is when we 

 find each ray of the simple rectangulated hexradiate 

 spiculum terminated by either three, four, or eight symme- 

 trically disposed spicula, as represented by Figs. 189, 190, 

 191, and 192, Plate VIII, and their terminal secondary 

 radii are either acute or spinulate. 



A still further amount of development is apparent in 

 the beautiful Floricomo hewradiate form represented by 

 Figs. 193 and 194, Plate VIII. 



The central radii consist of six rectangulated primary 

 rays of equal length, with slightly expanded terminations, 

 from each of which there issues seven or more petaloid 

 secondary spicula, the whole forming one of the most 

 beautiful simulations of a flower imaginable. 



Each petaloid spiculum is slender at its proximal termi- 

 nation, and continues to be so until near its distal end, 

 where it expands laterally, and presents a nearly sepai- 

 circular concavo-convex termination, with a beautiful 

 dentate margin, the number of the dents being usually 

 seven. Each of the petaloid spicula curves gently outward 

 from its base, the flowing hne returning towards the 

 central axis of the flower at about half of its height from 



