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XXXIII. DESCRIPTIONS OF THREE SPECIES OF SPONGE, CONTAINING 



SOME NEW FORMS OF ORGANIZATION.* 



By J. S. Bowerbank, Esq., F.G.S. 



THE first specimen described in this communication, \\3LS-dHalichondria, 

 which the author has named //. Johnstoniana, in honour of Dr. John- 

 ston of Berwick-upon-Tweed. The sponge is sessile, massive, and has a 

 smooth encrusted surface, of a dark iron-grey colour ; the interior is of 

 a dull yellow colour, and much resembles the crumb of bread. This 

 sponge is remarkable for the great variety in the forms of the silicious 

 spicula, of which the author described three distinct kinds, each of 

 which is characteristic of a separate part of the animal : 1st. Those of 

 the skeleton, which are mostly simple and slightly curved, having hemi- 

 spherical terminations ; they are occasionally tri- radiate or multi- radiate, 

 and frequently branched. 2nd. Those of the interstitial fleshy matter 

 of the sponge ; these are minute stellate bodies, having their rays atten- 

 uating regularly to their apices, the number of the rays varying from 

 three to ten or twelve. 3rd. The spicula of the crust or surface of 

 the sponge ; they are very minute and somewhat fusiform, terminate 

 abruptly, and have their surfaces regularly tuberculated. The author 

 also described a fine vascular tissue, which he observed on the surface 

 of the great excurrent canals. The gemmules are oval bodies, having a 

 silicious crust, which is filled with minute spicula. This species was 

 found attached to the Thatcher Rock, near Torquay, Devonshire. 



The second sponge described belonged to the new genus Duseideia, 

 proposed to be established by Dr. Johnston in his " History of British 

 Sponges." 



This species was sent from Sydney, Australia, by Rupert Kirk, Esq., 

 after whom it is named, D. Kirkii. It is sessile, massive, and some- 

 what compressed. The skeleton is coarsely fibrous, and coralloid in 

 appearance, having numerous grains of sand separately imbedded in its 

 substance. The grains are not imbedded in the fibre from pressure 

 through the external surface, but they occupy its very centre ; each 

 grain being separately encrusted by the cartilaginous matter of the 

 skeleton, and the whole being surrounded by a thick coating of the same 

 substance. The author described at length the mode in which this 



* Abstract of a paper read at the Microscopical Society of London, Nov. 24th, 

 1841. Communicated by the Author. 

 VOL. I. M 



