1873.] DR. J. S. BOWERBANK ON THE SPONGIAD.E. 9 



Sab. Unknown {Mr. Thos. Ingall). 

 Examined in the dried state. 



I received this sponge from my late friend Mr. Thomas Ingall in 

 1861. He purchased it with other specimens, the localities of which 

 were unknown. The specimen is evidently in a young and some- 

 what immature state, and it is very probable that its form would 

 undergo considerable modification in a more fully developed condi- 

 tion ; but even in its present state it is a very remarkable species. 

 The surface is even but very rough to the touch, in consequence of 

 the projection of the radii of many of the large bifurcating pateuto- 

 ternate connecting spicula. Although so young, there are already 

 two well-developed oscular areas upon its surface — one in a rather 

 deep depression, and the other nearly level with the external surface. 

 Very little remains of the dermal membrane ; but what there is of it 

 is crowded with the minute attenuato-stellate retentive spicula, 

 among which there are a very few of the larger subsphero-stellate 

 oues. The acerate tension-spicula are scattered on the surface of the 

 membrane and are rather few in number. The same spicula that 

 occur in the dermal membrane are found dispersed over the surface 

 of the interstitial ones, but they are much fewer in number than on 

 the dermal membranes. . 



It is a remarkable circumstance in this specimen that many of 

 the connecting patenti-ternate spicula, the triradiate heads of which 

 in other species of Geodia are attached to the inner surface of 

 the dermal crust of the sponge, in this one are projected forward to 

 such an extent through the stratum of siliceous ovaria that their 

 radii are seen emerging immediately at the dermal surface, while 

 others are seen at and near the inner surface of the dermal crust. 

 This diiference in the disposition of these spicula from those in other 

 species of the same genus may probably be accounted for by the 

 fact that the specimen under consideration is most likely in an 

 early stage of its growth and development, and that in future exa- 

 minations of larger and more completely developed individuals the 

 connecting spicula will be found occupying their usual positions 

 immediately beneath the dermal crust. 



The recurvo-ternate spicula occupy their usual position beneath 

 the dermal crust ; their long slender shafts are incorporated with 

 the skeleton-fasciculi, their heads appearing in the intermarginal 

 cavities. 



The progressive development of the bifurcating patentoternate 

 connecting spicula is exceedingly well illustrated in this sponge. 

 They are first observed to be small and slender with simple patento- 

 ternate radii acutely terminated ; and in this form they remain, 

 gradually increasing in length and stoutness until they attain the 

 size represented by fig. 5, Plate II. As they approach their com- 

 plete state of development the bifurcations of the radii become 

 more or less produced, but frequently in a very unequal manner, as 

 in fig. 6, the furcations being developed on one or two of the 

 primitive rays, while the third remains simple ; but when their 



