Mr. A. Hancock on new Species of Excavating Sponges, 239 



a fine point at one extremity; the other has usually two heads — 

 one terminal or nearly so, the second about one-third down the 

 shaft; the terminal head is frequently wanting : the third form 

 is about -g^^-o inch long, rather stout, cylindrical, usually irregu- 

 larly bent or angulated, and strongly spined, with the extremities 

 obtuse. 



A few additional specimens have occurred on the Northumber- 

 land coast. The sponge, when dry, is of a pale yellow-ochre 

 colour. 



Cliona Alderi. 



Spicula of two kinds, — the first pin-like, -j^-^ inch long, mo- 

 derately thick, slightly bent, with a small head near one end, 

 and tapering to the other extremity ; the second form is scarcely 

 shorter than the first, and has one end truncate, the other 

 pointed, and is decidedly bent in the centre. 



Sponge, in a dried state, of a yellowish-brown colour. 



Cliona lobata. PI. VII. fig. 6. 



Spicula of two kinds, — the first -^ inch long, not very slen- 

 der, mostly a little bent, and brought gradually to a sharp point 

 at one end, the other with an irregularly rounded head, some- 

 times slightly elliptical, and generally not exactly terminal : the 

 second kind, which is ^-^-o i^ich long, is cylindrical, rather stout, 

 arched, and zigzagged, being six or seven times angulated; it is 

 strongly spinedj particularly at the angles; the extremities are 

 obtuse. 



I am indebted to ^Ir. Charles Adamson, of Newcastle-upon- 

 Tyne, for the second specimen I have seen of this very distinct 

 species : it is in the shell of an oyster obtained from the rocks 

 on the west coast of Scotland. The dried sponge is of a dark 

 snufi*- colour. 



After a careful perusal of the above descriptions of the spi- 

 cula, few naturalists, I believe, will doubt the existence of more 

 than one species of British excavating Sponge. 



The foreign species, which are undoubtedly very numerous, 

 exhibit a considerable variety of spicula, though the prevailing 

 forms are similar to those found in the British species. A few 

 have only the pin-like kind, in this respect resembling C. celata; 

 but by far the greater number have either two or three kinds, as in 

 C. lobata and C Northumbrica. The following descriptions are 

 of four well-marked foreign species that have recently come under 

 my notice : — 



Cliona vermifera, PI. VIII. fig. 2. 



Sponge, when dry, of a pale yellow-ochre colour; branches 



