BRITISH SPONGIAD^E. 83 



Genus Tethea, Lamarck. 



Section * Skeleton spicula, acerate. 



1. Tethea cranium, Lamarck. 



2. Cottingsii, Bowerbank. 



3. Schmidtii, Bowerbank. 



Section * * Skeleton spicula, acuate. 



4. Tethea lyncurium, Johnston. 

 Section * * * Skeleton spicula, spinulate. 



5. Tethea spinularia, Bowerbank. 

 1. Tethea cranium, Lamarck. 



Tethea cbanium, Johnston. 



Sponge. Ovoid or subspherical, sessile. Surface even, 

 strongly hispid. Dermal coat thick, abundantly furnished 

 with short, stout, fusiformi-acerate spicula surrounding 

 the large defensive fasciculi at various angles to their 

 axes, also profusely furnished with minute sigmoid 

 bihamate spicula, dispersed irregularly. Dermal 

 membrane thin, pellucid. Oscula and pores incon- 

 spicuous. Spicula of the skeleton fusiformi-acerate, 

 large and long. Defensive spicula external, collected 

 in fasciculi ; fusiformi-acerate, large, and long ; fusi- 

 formi-porrecto-ternate, and a few fusiformi-recurvo- 

 ternate very long and slender. Sarcode abundantly 

 furnished with minute sigmoid- bihamate spicula. 

 Gemmules internal, lenticula, surface smooth, very 

 tough and strong ; of two distinct sorts. The first 

 furnished abundantly with slender fusiformi-acerate 

 spicula radiating in fasciculi from the centre to near 

 the surface of thegemmule. The second furnished abun- 

 dantly with slender fusiformi-acerate; slender uni- 



