1873.] DR. J. S. BOWERBANK ON THE SPONGIAD^E. 329 



have had a small collection of oscula at the bottom of it originally ; 

 but the dilapidated condition of the specimen allows of nothing 

 more definite than a conjecture on the subject. The porous areas 

 were not evenly dispersed over the surface ; and two or three small 

 groups of them only were apparent, marked by the usual pitted 

 appearance that indicated the presence beneath of the intermarginal 

 cavities. On this portion of the specimen the dermal membrane 

 was in a tolerably perfect condition, and contained an abundance of 

 minute sphero-stellate spicula, like those of the interstitial mem- 

 branes, in which they were also rather abundant. These minute 

 organs are very characteristic of this species. The spherical centre 

 of a fully developed one measured ytW i ncn diameter, and the 

 spiculum between the extreme apices -j-gVcr in ch. They are very 

 similar in form to the sphero-stellate spicula of Tethea lyncurium, 

 but are very much more minute, and the number of the radii is 

 much greater ; but they resemble those of T. lyncurium very much in 

 their conical form. I have not before found this form of spiculum 

 in the sarcode of a Geodia. The diameter of a fully developed 

 ovarium was -§-i- 3 - inch. The cuneiform spicula of which they are 

 composed are large in proportion to the size of the ovarium, and the 

 the distal extremities are much angulated. 



Geodia patjpera, Bowerbank. (Plate XXXI.) 



Sponge massive, coating ; surface even, smooth. Oscula simple ; 

 congregated in depressed areas. Pores congregated. Dermal mem- 

 brane thin, pellucid. Connecting-spicula attenuato-expando-temate, 

 variable in size and proportions, rather few in number. Skeleton 

 abundantly spiculous ; spicula fusiformi-acerate, comparatively small 

 and short. Interstitial membranes — tension-spicula subfusiformi- 

 acerate, small and slender ; retentive spicula cylindro-stellate, variable 

 in size and structure, and very minute cylindro-stellate ; radii short 

 and stout. Ovaria globose ; cuneiform spicula of adult specimens 

 comparatively large, distal ends prominently angulated. 



Colour, in the dried state, cream-white. 

 Hub. Unknown. 

 Examined in the dried state. 



I am indebted to Mr. Jeremiah Slade for my knowledge of this 

 species. It was purchased at a public sale of specimens of natural his- 

 tory from various localities. It is based on an irregular mass of coral, 

 an Astrcea, about 4 inches in diameter, on which has grown a speci- 

 men of Gorgonia flabellum and a compound tunicated mollusk ; the 

 latter has very nearly covered the Geodia, which is about 2 inches in 

 length, and rather exceeding an inch in breadth. The specimen has 

 suffered much by maceration, and nearly the whole of the dermal 

 membrane has been destroyed; the little that remained was thin 

 and translucent, but in such a condition as to afford no other 

 specific characters. In sections made at right angles to the dermal 

 surface, large intermarginal cavities were apparent, passing through 

 the dermal crust from its outer to its inner surface, which is covered 



