BRITISH SPONGIAD^E. 239 



I am indebted to Dr. Grant for a fine specimen of this 

 sponge which he found on the shingle opposite Mile-town, 

 Sheerness, Sheppey. His description of the external cha- 

 racters of the species is so good that I cannot do better 

 than quote it for the information of the reader. " When 

 coalita is young, its branches are long and slender ; they 

 shoot in all directions to seek for points of attachment and 

 adhere to, or envelop every thing they meet with, living 

 or dead, animal, vegetable, or mineral; wherever the 

 branches cross or touch each other, they form a perfect 

 union ; sometimes the animal spreads as a layer over an 

 oyster shell, or covers a rock like a convoluted bush, or 

 like the root of a Eucus, or forms a cement connecting into 

 a mass all manner of shells, stones, or broken glass ; some- 

 times it forms an irregular mass, with a perfectly smooth 

 surface, without any point of attachment, rolling to and 

 fro at the mercy of the waves. As it advances in life, its 

 colour assumes a darker shade, with a tinge of brown ; it 

 becomes less smooth on the surface and loses its trans- 

 parency." 



The specimen represented in Plate XII, fig. 1, in Dr. 

 Johnston's ' History of British Sponges,' and that presented 

 to me by Dr. Grant, very closely resemble each other, so 

 that no doubt can remain of the identity of the species. 



The skeleton structure of this sponge is more uniform 

 than that of H panicea ; the interspaces are very much 

 more equalised, although in no degree symmetrical ; and 

 as a type of the acerate division of Halichondria, it is 

 certainly better than H. panicea. 



The specimen marked Spongia coalita in Montagu's 

 collection of sponges in the possession of Dr. Grant is 

 certainly Hal. simulans of Dr. Johnston, and not Spongia 

 coalita of older authors as Montagu believed. I doubt 

 very much that the species designated Halichondria coalita, 

 by Johnston, is the same as that figured by Miiller in Jris 

 ' Zoologia Danich,' t. cxx, as Spongia coalita, and presumed 

 by him to be the same as Ellis's Spongia ramosa Brittanica, 

 which there is no question is the species designated by 

 Johnston Halichondria oculata ; but Esper's Spongia sub- 



