312 A MONOGRAPH OF THE 



was obtained from the Northumberland coast. I have also 

 since received fine specimens from my friends, Mr. Joshua 

 Alder and Mr. Peach ; that from the latter gentleman and 

 the one from Mr. Mc An drew have the whole of their 

 tissues in a remarkably fine state of preservation. The 

 colour of the glove-shaped specimen from Orkney in its 

 dried state is a rather deep red brown, while those of the 

 Newcastle Museums, from the thorough washing thev have 

 undergone; are of a light gray. 



From the mode of the growth of this sponge it is pro- 

 bable that it is perennial. It is not developed at once, 

 but by a series of efforts which may be readily made manifest 

 by holding the sponge up to the light, when the commence- 

 ment and termination of each stage of groAvth is strikingly 

 apparent. I have seen as many as six of these stages of 

 growth in a branch about eight inches in length. In the 

 old and fully mature portions of the sponge, the central 

 parts of the lines of the skeleton-structure do not occupy 

 more than one third of the diameter of the primary line of 

 the skeleton, the remaining external portion being solid 

 keratode ; but the newly-formed parts of the rete of the 

 distal extremity of the last of the periodical additions to 

 the sponge have much the appearance of that of a Des- 

 macidon, consisting of a compact and continuous fasciculus 

 of spicula, with little or no indication of an external sheath 

 of keratode. 



In the older portions of the sponge, the interstices of the 

 skeleton do not appear to be filled with sarcode, but the 

 rete is covered with it, and a few of the anchorate spicula 

 may be seen imbedded in it ; but, in the young and grow- 

 ing portions of the sponge, the interstices are furnished 

 with membranes thickly coated with sarcode, which is lite- 

 rally crowded with the equi-anchorate spicula. These 

 organs are very remarkable in their form ; the middle por- 

 tion of the shaft is curved outward in the usual manner, 

 and the two extremities are bent into hooks like a simple 

 bihamate spiculum, but instead of the distal portion of 

 the hooks continuing in accordance with the primary lines 

 of projection from the middle of the shaft near each end of 



