BRITISH SPONGIAD.E. 211 



34. Hymeniacidon clavigera, Bowerbank. 



Sponge. Massive, sessile ? Surface uneven, deeply pitted, 

 more or less hispid. Oscula and pores unknown. 

 Dermal membrane thin, pellucid, spiculous ; spicula 

 same as those of the skeleton. Skeleton : spicula at- 

 tenuato-clavate or spinulate, large and very long, 

 variable in size, often more or less flexuous. Internal 

 defensive spicula, attenuato-clavate, entirely spined, 

 variable in size ; clavate terminations mostly exaxial, 

 frequently large and long ; spines numerous, small. 

 Sarcode abundant, amber coloured. 



Colour. Dried, light gray. 



Locality. Firth of Clyde, Rev. A. M. Norman. 



Examined. In the dried state. 



This species is described from a very incomplete and un- 

 satisfactory specimen, which is apparently a portion only 

 of the perfect sponge ; but the characters, as far as they go, 

 are very distinct from those of any other species of the 

 genus. The specimen is nine lines in length, and about 

 four lines in thickness and breadth. The characters of the 

 surface are much obscured by an abundant growth of a 

 Mucor, and I could not detect either oscula or pores. In 

 the living state it is probable that the surface would neither 

 be deeply pitted nor hispid. 



The spicula of this sponge present excellent specific 

 characters. Those of the skeleton are spineless, and are 

 frequently very long and slender, and they are abundantly 

 dispersed on the interstitial membranes ; they are variable 

 in size, and often flexuous. The basal enlargement most 

 frequently presents a more or less clavate form, but occa- 

 sionally they are cylindrical. The internal defensive spicula 

 are also exceedingly variable in length and thickness, and 

 the clavate base is mostly exaxial, the deflexion frequently 

 being to a very considerable extent. The spines are abun- 



