298 dr. j. s. bowerbank on the spongiadjE. [May 5, 



7. Contributions to a General History of the Spongiadce. 

 By J. S. Bowerbank, LL.D., F.R.S., &c— Part VI. 



[Received April 4, 1874.] 

 (Plates XLVI. & XLVII.) 



Geodia carinata, Bowerbank. (Plate XLVI. figs. 1-5.) 



Sponge sessile, coating stems of Gorgonia or Fuci. Surface 

 smooth, but furnished with numerous longitudinal carinas. Oscula 

 simple, dispersed, few in number. Pores inconspicuous. Dermal 

 membrane thin and pellucid, furnished abundantly with multiangu- 

 lated cylindrical spicula. Skeleton — fasciculi multispiculous, com- 

 pact ; spicula attenuato-spinulate, bases coincident. Interstitial 

 membranes furnished abundantly with arborescent elongo-subsphero- 

 stellate retentive spicula, variable in degree of development. Ovaria 

 oval or kidney-shaped, component spicula slender and delicate. 

 Surface-rete very minute. 



Colour in the dried state light fawn-yellow. 

 Hub. South Sea (Mr. Thos. Ingall). 

 Examined in the dried state. 



I received the figured specimen of this singular species from my 

 late friend Mr. Thos. Ingall in 1854, and I then described and 

 named it in MS. ; and subsequently the multiangulated cylindrical 

 spicula of the dermis were described and figured in my paper on the 

 " Anatomy and Physiology of the Spongiada," in the Philosophical 

 Transactions of the Royal Society for 1858, p. 314, plate xxvi. 

 fig. 10, and also the arborescent elongo-subsphero-stellate reten- 

 tive spicula of the interstitial membranes in p. 308, plate xxv. 

 fig. 19 of the same part for 1858. Shortly after I had examined 

 and named the species I saw a similar specimen in the British 

 Museum arranged among the Corals ; and I stated to Dr. Baird that 

 it was a sponge and told him the name I had assigned to it, and he 

 forthwith removed it from the case and placed it among the Sponges. 

 Subsequently I obtained a second specimen by purchase in the year 

 1864. The whole three specimens were similarly parasitical and 

 very closely resembled each other in their external characters, and 

 especially so in their singularly carinated striation. On taking 

 sections at right angles to the surface of the sponge, I found that 

 these elevated ridges were produced by the projection of lines of 

 skeleton-fasciculi through the dermal crust of the sponge to imme- 

 diately beneath the dermal membrane, but in no instance did they 

 appear to perforate that organ. The greater portion of these cari- 

 nated elevations were in a longitudinal direction ; but occasionally 

 short transverse ridges are found connecting the longitudinal ones 

 with each other. 



The dermal membrane is thin and pellucid, and when in a fine 

 state of preservation it is literally crowded with innumerable minute 



