HALICHONDRIA. Ill 



Plate IV. Fig. 4, 5. 



Spoiigia cinerea, Grant in Edin. New Pbil. Jourii. ii. 204, pi. 2, 

 fig. 3 : (the spieuliim) copied in Blainv. Actinol. pi. 94, fig. 3. 



Halichondria cinerea, Flem. Brit. Anim. 521. 



Spongia CBerulea ? Risso, L'Europ. Merid. v. 373. Delk Chiaic, 

 Anim. s. Vert. Nap. iii. 113, tav. 37, fig. 11. 



Spongia pulverulenta, Scouler MS. 



Hah. Frith of Forth, very rare, Dr Grant. Cunnamara 

 and Dublin Bay, Wm. M'Colla and A. H. HassalL 



Sponge forming an irregular crust of a uniform hair-brown or 

 ash-grey colour, about a quarter of an inch in thickness, soft 

 and pulvenilent when dry, and of a very fine sponge-like texture. 

 The surface is even and smooth without visible pores, and the 

 oscula are indistinctly marked. The structure is reticular, but 

 the net-work is formed, not by a horny fibre, but by the spicula 

 alone, w'hich are disposed so as to become the frame-work of 

 small quadrangular meshes of unequal sizes, held together by a 

 very small proportion of glutinous matter. The spicula are si- 

 milar to those of H. Montaguii but shorter and straighter. The 

 species is evidently littoral, for the specimen before me has en- 

 veloped in its growth some leaves of the Zostera marina. 



This sponge varies a good deal in colour, so that Dr Scouler's 

 name for it is much preferable to that which it bears in right of 

 priority, and has also the advantage of expi'essing the remarka- 

 ble friability, which may be considered as the principal characte- 

 ristic of the species when dried. It is thus described by Dr Grant : 

 — " I met only with a single specimen of this sessile species, 

 about two years ago, in the Firth of Forth, and I have not since 

 observed it on any other coast. It grew on the inclined side of 

 a rock, had an irregular outline, and was about three inches in 

 length, one in breadth, and half an inch in thickness. My at- 

 tention was attracted to this s])ecimpn, from its perfect resom- 



