ACCOUNT OF BRITISH SPONGES. 63 



fectly straight, and gradually tapering to a point. 

 A specimen in my cabinet, taken on the coast of 

 Devon, has not less than a dozen main branches, 

 some of which are eleven inches long. A figure 

 of a branch of this, and of the oculata *, are given 

 together, in order to shew the difference of their 

 usual growth, as it is probable they have some- 

 times been confounded. 



A comparative description has been considered 

 in some degree essential for the discrimination of 

 these two species, as the dichotGma has not, I be- 

 lieve, been considered as British, but was origi- 

 nally described by Mr Ellis as a production of 

 the coast of Norway. The rows of cells which 

 the oculata is described to possess on the margin, 

 and which project a little, does not form a charac- 

 ter of distinction, being equally applicable to 

 dichotoma ; but perhaps in this last, the cells are 

 more disposed over the whole surface. Both 

 species are yellowish when fresh. 



Berkenhout is the only one who mentions this 

 species as a native of the Cornish and Yorkshire 

 coasts, but on what authority we are not inform- 

 ed. 



f2 



^ Plate vi. fig. 2. 



