BRITISH SPONGIADiE. 351 



Colour. Dried, light gray. 

 Habitat. Shetland, Mr. C. W. Peach. 

 Examined. In the dried state. 



This sponge was sent to me with many others by my 

 friend, Mr. Peach. It was dredged by Mr. J. G. Jeffreys at 

 Shetland in 1864. It is but a fragment, about two inches 

 high, based on the remains of a Coral, and is so completely 

 water worn that very few of its specific characters are 

 available for description. I have stated that the dermal 

 membrane is aspiculous, but it is really very doubtful 

 whether the minute portion of membrane remaining at the 

 present surface of the sponge is truly dermal, or is inter- 

 stitial ; the latter membrane, fragments of which remain in 

 good preservation in the interior of the sponge, is undoubt- 

 edly spiculous, and the presumption is that the dermal one 

 would likewise be so. Indecisive as the other characters 

 are, those of the spicula of the skeleton are perfectly de- 

 monstrative. They are not only unlike those of any known 

 species of Desmacidon, but are unknown in any other 

 British sponge. They are large and long, somewhat 

 slender, and slightly fusiform ; but their peculiarity consists 

 in an irregular constriction of the shaft near its basal 

 extremity. This commences at about one diameter of the 

 largest part of the shaft from the extreme base, and con- 

 tinues for from one to three diameters up the shaft, which 

 then gradually increases in its diameter, as in the usual 

 form of a fusiform spiculum. The sudden constriction of 

 the shaft near its base gives that portion of it the appear- 

 ance of an elongo-curvato-spinulate termination ; but in 

 some of the spicula where the constriction is absent or very 

 slightly produced, the spinulate character is entirely obsolete. 

 The space of constriction is not always of equal diameter, 

 and sometimes one or two minor constrictions are observ- 

 able in its length. I could not detect the tension and 

 retentive spicula of the interstitial membranes either among 

 the spicula, separated by the aid of boiling nitric acid, or in 

 portions of the sponge mounted in Canada balsam ; the 

 sarcode on the surfaces entirely concealing them ; but in 



