142 A MONOGRAPH OP THE 



I am indebted to my friend Mr. Barlee for this interest- 

 ing species. I received four specimens, three of which 

 were coating small pebbles. None of them exceeded four 

 lines in diameter, and the thickness not more than that of 

 a sheet of writing paper. The colour is a light buff yellow, 

 and with a lens of two inches focus the long spicula may be 

 seen projecting from the surface of the sponge, like minute 

 bristles. By the aid of a Lieberkuhn and a power of 100 

 linear, the surface appears very uneven, full of abrupt 

 depressions and elevations, and a few minute simple oscula 

 were apparent. 



When a portion of the sponge was removed from the 

 stone and mounted in Canada balsam, the dermal mem- 

 brane appeared to be very delicate, and to be lined with a 

 thin coat of sarcode, but I could not either by this mode 

 of mounting, or by any other means, detect the spicula of 

 that membrane in situ. On treating a piece of the sponge 

 with boiling nitric acid, in a small dished cell, I obtained 

 them in considerable numbers, and the greater portion of 

 them were collected in regular fasciculi ; and from this 

 mode of arrangement, and the peculiarities of their struc- 

 ture, there is no doubt in my own mind that they were 

 liberated by the action of the acid from the dermal mem- 

 brane. They are so slender that they require a linear 

 power of 500 or 600 to define their structure and propor- 

 tions accurately. The skeleton and external defensive 

 spicula appear enormously large in proportion to the thick- 

 ness of the sponge and its remaining tissues. The whole 

 of them have the base firmly cemented to the basal mem- 

 brane, whence they are projected through the mass of 

 sarcode, the dermal membrane, and far beyond its surface, 

 and at about right angles to it. 



The basal membrane of this sponge presents a novel and 

 very singular appearance. It is abundantly furnished with 

 inequi-acerate vermiculoid spicula lying on the surface of 

 the membrane, and presenting an appearance very like a 

 congregation of the vibrioses of sour paste. No two of 

 them are alike in their contortions, length, or thickness, 

 and in their disposition they pass under and over each 



