BRITISH SPONGIADvE. 91 



from their junctions with the skeleton fasciculi beneath, and 

 meeting each other at their distal portions, form a uniform 

 and continuous surface for the support of the intermarginal 

 cavities. The external defensive spicula are rather nu- 

 merous. In the dried condition of the sponge they are 

 projected about half their length through the dermal mem- 

 brane ; the bulbous bases of these spicula are strongly 

 produced, the shafts are often long and flexuous, and occa- 

 sionally they are sub-fusiform. Although these spicula are 

 so abundant in the dermal and intermarginal membranes, 

 I could not detect them in the deeply seated interstitial 

 ones, while the same tissues were crowded with both forms 

 of stellate retentive spicula. The attenuato-stellate spicula 

 are three or four times the diameter of the cylindro-stellate 

 ones, and frequently have not more than five or six rays, 

 while the latter have usually ten or twelve rays. This 

 species, in its habit and structural peculiarities, closely 

 resembles T. Collingsii. The skeleton and connecting spi- 

 cula are of the same form in each, but those of the skeleton 

 in T. ScJimidtii are shorter, and less in diameter than those 

 of T. Collingsii. The connecting spicula of the former are 

 also shorter and stouter than in the latter species, but 

 although thus less in size they have the ternate terminations 

 much larger than in T. Collingsii. Thus the differential 

 characters of the two species are not readily apparent to a 

 hasty investigator, but by a more minute examination when 

 mounted in Canada balsam, with the aid of a microscopical 

 power of about one hundred linear, and by a close obser- 

 vation of the dermal spicular characters, the two species 

 may be readily distinguished. 



I have named this species after Dr. Oscar Schmidt, 

 Professor of Zoology in the University of Gratz, who has 

 done so much to advance our knowledge of the European 

 species of sponges, by the publication of his valuable work 

 on the sponges of the Adriatic. (' Die Spongien des Adria- 

 tischen Meere.') A specimen of this species was found 

 between two stones, at extreme low-water mark, by the 

 Rev. A. M. Norman, 1865. 



