12 DR. J. S. BOWERBANK ON THE SPONGIADjE. [Jan. /, 



Geodia in^equaeis, Bowerbank. (Plate II.) 



Sponge irregularly massive, sessile ; surface minutely pitted. Os- 

 cula congregated in irregular groups. Pores congregated in minute 

 pits. Dermal membrane obsolete. Skeleton-fasciculi loosely con- 

 structed ; spicula ratber few in number, inequicylindrical, variable in 

 size. Connecting spicula expando-ternate ; radii short ; shafts long, 

 slender, and attenuating. Interstitial membranes spiculous ; tension- 

 spicula inequicylindrical, long and very slender, few in number; 

 retentive spicula attenuato-stellate, very variable in size, number, and 

 degree of attenuation of their radii, comparatively few in number ; 

 also cylindro-stellate, very minute, radii numerous and short, very 

 abundant. Ovaria spherical or somewhat oval, slightly depressed. 



Colour in the dried state cream-white. 

 Hab. Unknown. 

 Examined in the dried state. 



I received this sponge with other specimens from my late friend 

 Mr. Thomas Ingall in 1861, without any account of its locality. 

 The specimen has every appearance of having been freely floating 

 about in the sea for some time, as no traces of a basal attachment can 

 be detected on any part of it, and at the part indicated in fig. IS, aa, 

 there is a group of sand-worms which have built their cases upon its 

 surface. I could not detect any portion of a dermal membrane ; but, 

 from the excellent state of preservation of the interstitial structures of 

 the sponge, there is no doubt of its being alive when taken from the 

 sea. Several groups of oscula dispersed over the surface represented 

 in the figure, and especially on the part immediately above the open 

 mouths of the sand-worm-cases at a ; but on the reverse of the figure 

 there are no oscular groups. The oscula are rather small ; and, in 

 consequence of the absence of the dermal membrane, the depressed 

 areas of the distal ends of the intermarginal cavities are almost as 

 large as the oscula ; but a careful observation soon enables us to dis- 

 criminate the one from the other. 



The skeleton-spicula are very loosely combined in the skeleton- 

 fasciculi, and they are rather few in number ; their inequicylin- 

 drical form affords an excellent specific character. It is the only 

 Geodia in which I have yet seen that form of skeleton-spiculum ; 

 they vary to some extent in size, but the form is constant. 



The stellate retentive spicula of the largest, description vary to 

 a considerable extent ; their extremes are well represented by figures 

 21 and 22, Plate II. In the form represented by fig. 21 the 

 radii are very numerous and acutely conical, while in that of fig. 22 

 they have very much more slender radii and comparatively few of 

 them ; but intermediate forms in every degree may be readily found 

 among them. Their average diameter is -g4 T inch. The smaller de- 

 scription, the minute cylindro-stellate ones, are very numerous and 

 much more constant in their forms than the larger ones ; their aver- 

 age diameter is -g^m inch. The interstitial membranes are rather 

 thickly coated with dark amber-coloured sarcode, and in many parts 

 they are quite crowded with the two descriptions of stellate spicula. 



