ADDITIONS. 357 



it gradually expands until it attains a breadth of three 

 and a quarter inches at its distal extremity, a height 

 of three and three quarter inches, and a thickness of 

 one and a half inch. One side of the sponge is 

 gibbous, and the other flat and worn as if by attrition. 

 On the convex side there are numerous dispersed 

 simple oscula, one only exceeding the eighth of an inch 

 in diameter. In form, size, and general appearance it 

 differs to a great extent from the figured specimens of 

 the species represented in Vol. Ill, Plate LI, figs. 1 

 and 2. But in its anatomical characters it is identical 

 with the structures of those specimens, and strikingly 

 so with the dermal peculiarities of the sjoecies ; the 

 large irregular aspiculous porous areas being very 

 abundantly produced. 



Desmacidon copiosa, Plate LXXXII. 



Among some British sponges received from Miss 

 Oliver, there was a specimen of this species two 

 inches in length and rather more than one inch in 

 width, and about half an inch in thickness. When 

 alive it was of a dull flesh-red colour and rather firm 

 to the touch, and in its structure it was much more 

 solid and compact than the type-specimen represented 

 in Plate LXXXII, fig. 2. I received also at the same 

 time an oyster-shell encrusted with Microciona fictitia, 

 and upon the shell there grew a specimen of sertularia 

 filicula, parasitical, in the midst of which there was 

 another specimen of D. copiosa, binding the fronds of 

 the zoophyte together into a mass an inch and a half 

 in length by an inch in width. This specimen in form 

 was very like the type one. 



Chalina Flemingii, Plate LXVIII. 



Among some old stones received from my kind 

 friend Mr. C. W. Peach, I found a specimen of a 



