BRITISH SPONGIAD^. 231 



the mass, nine inches by six at the base, is covered by very 

 large fistulse, some of which are six inches in height, while 

 others not exceeding three inches in length have an external 

 diameter of more than one and a quarter inches. In all 

 these cases the inner surfaces of the fistulas are abounding 

 with simple oscula, while on the general surface of the 

 sponge there is scarcely one to be seen. 



The pores are frequently beautifully displayed in dried 

 specimens of this sponge. Figure 303, Plate XIX, vol. i, 

 represents a portion of such a specimen. The variations of 

 their character on the surface of the same sponge is often 

 extremely great. In one spot it will be beautifully reticu- 

 lated, and the area of every one of the meshes will be 

 occupied by several pores, while within the quarter of an 

 inch of the reticulated part the surface will be entirely 

 devoid of either reticulations or pores, and in this case the 

 dermal membrane is frequently furnished with a thickly 

 matted lining of spicula without the slightest vestige of 

 arrangement. Dr. Johnston, in his ' History of the British 

 Sponges,' page 147, has described a species found on the 

 shore of the Isle of Man by the late Professor Edward 

 Forbes, under the name of Halichondria sevosa. I have 

 been unable to detect any organic difference between the 

 type specimen now in the British Museum and the common 

 specimens of Halichondria panicea; and a careful in- 

 spection of the type specimen leads me to believe that the 

 sponge was not erect, but that it had grown coating a 

 Fucus, or some other such substance. Upon no part of the 

 margin is there the slightest indication of a base or attach- 

 ment. The " Fatty" character described by Dr. Johnston 

 exists only in its appearance to the eye, the texture beneath 

 the microscope is exactly that of a young thin coating 

 specimen of H. panicea, and the surface in its present state 

 is quite smooth. 



There can be no reasonable doubt that the " Sponge-like 

 crum of bread" described by Ellis in his ' History of 

 CoraHines,' No. 2, page 80, Plate XVI, d, and that desig- 

 nated H. panicea by Dr. Johnston in his 'History of 

 British Sponges' are identical ; but the author of the latter 



