32 



VI. — On the Keratose or Horny Sponges of Commerce. 

 By James Scott Bowerbank, F.G.S., &c. 



Read January 27, 1841. 



Until the publication of the valuable papers by Dr. Grant in the 

 ' Edinburgh New Philosophical Journal ' for 1827, but very little can 

 be said to have been known of the true structure and functions of the 

 sponge tribe. In the descriptions there given of the examination of 

 numerous British species, the learned Professor has not only made us 

 intimately acquainted with their general forms and structure, but he 

 has developed the mode of their propagation, and shown it to approx- 

 imate so nearly to that of the coral tribe, as to leave but little reason- 

 able doubt of the truth of their animal nature. I will not repeat the 

 evidences of the author to establish these facts, as the papers con- 

 taining the proofs are so easily accessible. It will be sufficient to ob- 

 serve that he has proved that the whole of these poriferous animals 

 are composed of a minute reticulated structure, which derives its sup- 

 port from a thread whose structure is either horny or cartilaginous, 

 hence called keratose ; or from the dispersion through its substance 

 of numerous siliceous or calcareous spicula. Accordingly as each of 

 these modes of structure prevails, the sponges are divided into various 

 genera, and among these there is one which contains the sponges of 

 commerce and other keratose species, which are said to consist of tu- 

 bular horny fibres, and to be destitute of spicula. It is this tribe that 

 I purpose making the subject of this communication. 



The investigations of Dr. Grant were in a great measure confined 

 to those orders of sponges which contain in great abundance either 

 calcareous or siliceous spicula : of these the only known British spe- 

 cies {Spongia pulchella) has been published by Sowerby in the ' Brit- 

 ish Miscellany,' as occurring on the southern and western coasts of 

 England. Dr. Fleming, in his ' British Animals,' p. 524, has thus de- 

 scribed the genus Spongia : — " Porous, the cartilaginous skeleton 

 simple, or destitute of earthy spicula." 



I was induced to investigate this tribe in consequence of having re- 

 cently received from my friend Rupert Kirk, Esq., of Sydney, Austra- 

 lia, about forty species of various genera of sponges, among which 

 were many exhibiting every appearance of being true keratose spon- 

 ges, and which, on a superficial examination, might reasonably have 

 been expected to be destitute of spicula, but upon examining small 



