130 A MONOGRAPH OF THE 



short, and conical, occasionally curved ; spines of the 

 shaft very stout, long, and recurved, especially so 

 towards the apex. Interstitial membranes ; spiciila 

 same as those of the dermal membrane. Basal mem- 

 brane abundantly furnished with internal defensive 

 spicula. Gemmules spherical, membranous, aspicu- 

 lous. 



Colour. — Alive, blood-red ;. in the dried state, nut-brown. 



Habitat. — Belfast Lough, Dr. Dickie; St. Catherine's 

 Bay, Jersey, Rev. A. M. Norman. 

 1 Examined. — In the dried state. 



This sponge coats the front of one of the valves of a 

 common mussel-shell for two inches in length and ahout 

 seven lines in breadth, and its greatest thickness is about 

 two lines. The surface is rough, from the partial destruc- 

 tion of the cuticle and the exposure of a number of sinuous 

 intermarginal canals. In its present condition its texture 

 is rigid, and of a nut-brown colour. In consequence of 

 the destruction of the dermal membrane to so great an 

 extent, I have been unable to determine with certainty the 

 characters of the oscula, but from the size and disposition 

 of the intermarginal canals which conveyed the excurrent 

 streams to them, it is probable they were small and diss 

 persed over the thicker parts of the sponge. The dermal 

 membrane is situated immediately above the terminations 

 of the columns of the skeleton ; small portions of its 

 remains, about a line and a half in diameter, were pellucid, 

 and abounded with its characteristic tension and retentive 

 spicula. The spicula of the skeleton are singular, from 

 having the bases furnished profusely with incipient spines 

 or tubercles for about the length of one diameter of the 

 spiculum, beyond which the shaft is completely devoid of 

 spines. The internal defensive spicula have their bases 

 profusely furnished with large conical or recurved spines 

 for about one diameter of the spiculum in length, and the 

 remainder of the shaft is more sparingly, but still abun- 

 dantly supplied with them, the spines becoming larger and 



