HALICHONDRIA. 101 



markablc tubulous condition of the branches originating in unas- 

 certained local causes, — but the, observations of Mr Bowerbank 

 have satisfied me that the suspicion is groundless. This excellent 

 naturalist and micrographer, who did me the favour of making 

 a comparative examination of the two species, w^rites me thus ; 

 " The spicula of H. oculata are thinner and somewhat straighter 

 than those of H. Montaguii, and the cartilaginous fibre surround- 

 ing them is more perfect and abimdant. The specimen of H, 

 oculata is a perfect skeleton, while that of both specimens of H. 

 Montaguii is covered with the fleshy matter of the sponge. The 

 two specimens of Montaguii agree perfectly with each other, and 

 are certainly a diffei'ent species from H. oculata, not only on ac- 

 count of the variation of structure mentioned above, but there 

 is a general aspect which is difficult to describe, but which is 

 sufficiently striking when seen with a power of 500 linear to im- 

 press the idea of their difi'erence immediately upon the mind." 

 Montagu referred this species hesitatingly to the Spongia tu- 

 bulosa of Solander (^EUis and Soland. Zooph. 188, tab. 58, 

 fig. 7.), from which it is undoubtedly distinct, and hence Dr 

 Fleming conferred on it the surname of the eminent discoverer, 

 whose essay on sponges, I may take this opportmiity of noti- 

 cing, Lamouroux has ascribed, with culpable carelessness, to 

 Mr Donovan. See Encyclop. Meth. art. Vers, ii. 327, &c. 



7. H. CoLUMB-iE, *' irregularly latticed by rounded inos- 

 culating branches ; spicida doidile-pointed and cwved.^^ 



Spongia Columbae, Walker, Essays, 96. 



Spongia cancellata, Soio. Brit. Misc. 131, pi. 60. Montagu in 



Werii. Mem. ii. 110. Turt. Brit. Faun. 208. 

 Scypha cancellata, Gray, Brit. PI. i. 358. 

 Halichondria Columbae, Flem. Brit. Anim. 521. 



Hub. South shore of Icolumbkil, Walker. Brighton in 

 Sussex, Mr Felloivs. 



*' It is of a round compressed shape, and about four inches 



