362 A MONOGRAPH OP THE 



The skeletons of this sponge are thrown up abundantly 

 on the shores of almost every part of the British coast, but 

 they are rarely found under such circumstances in good 

 condition. In this state they are of a light yellow colour, 

 and are very flexible, excepting near the basal portions. 

 They vary in height from a few inches to more than a foot, 

 and no two of them are alike in the ramification of their 

 branches. 



In a specimen of the sponge in this condition, rather 

 exceeding a foot in height, a transverse section of the stem 

 an inch above the base, had the keratose fibre very strongly 

 developed, and in many parts it was swollen into large 

 round or oval .tuberous masses, from which stout keratose 

 fibres emanated. At three inches from the base these 

 tuberous masses were increased both in number and in 

 size, and the stem up to this point being as hard and rigid 

 as a stem of wood. At six inches from the base, the kera- 

 tose concretions were very few in number, but the fibres 

 were still stout and short, but cylindrical in form, and the 

 sponge very much more soft and flexible ; at nine inches 

 from the base the diameter of the fibres was little more 

 than half that of those at six inches, and at every inch up- 

 ward it progressively decreased in size, until at the extreme 

 end of the sponge, although still maintaining its fibrous 

 character, the quantity of keratode was so small as to render 

 it doubtful whether the section represented a Chalina or an 

 Isodictya. The specimen under consideration was an old 

 and fully matured one, and had probably ceased growing 

 for a considerable time. In others very much shorter and 

 more flexible, the growing portions from the paucity of the 

 keratode surrounding the spicula so completely simulated 

 the structure of an Isodictya, as to be very liable to mislead 

 a young observer in his determination of the genus. 



I have obtained numerous specimens of this species from 

 the trawlers on the Diamond Ground, off Hastings, in the 

 living state. In this condition the sponge is soft and fleshy 

 to the touch, and has a considerable amount of green in its 

 colour, and when dried in this state it becomes rigid, and 

 of a dark dirty green colour. While living, the dermal 



