240 



Skeleton consisting of a confused mass of oxeas of various 

 sizes, and of somal microstrongyles, which form a thin but 

 compact dermal layer. 



Spicules. Megascleres. — Oxeas of various sizes, from 360 x 9 ju 

 to 1550 X 62 M, curved, often slightly centrotylote. 



Locality K. — Durnford Point, Natal, 90 fms. ; bottom, broken 

 shells. 



The new species is represented by one specimen, which is 

 firmly attached by a large base to Stelletta horrens, Kirkp. The 

 dimensions are 8x9x9 cm. 



For the most part the dermal layer has disappeared, the 

 eroded surface showing matted masses of spicules (oxeas). 



The new species possesses microstrongyles, usually centro- 

 tylote, these being probably modified euasters. 



In the genus Coppatias, as defined by Sollas, only one form 

 of aster, the euaster, occurs ; accordingly an enlargement of the 

 definition is necessary, if it is to include the present species. 

 The new definition of Coppatias would run : — Coppatiida', with 

 megascleres without order ; the microscleres being either 

 euasters or microstrongyles. 



Genus Tethya (Lamarck). 



Tethya magna, sp. n. 



Plate v., Fig. 6. Plate VI., Fig. 6a-d. 



Sponge oval or spherical, attached at the base by banyan-tree- 

 like rootlets, surface with well-marked conules in the young 

 state, expanding later into polygonal plates. 



Cortex including intercortical cavities. 



Pores in cribriform groups between the conules over certain 

 areas ; oscules not visible. 



Colour, in spirit, purple-brown ; on section, cortex silvery, 

 pith bright yellow. 



Spicules. Megascleres. — Strongyloxea 4805 x 75 m. 



Microscleres. Cortical spherasters 60-110 m in diameter, 

 sharp conical actines about 35 m. 



Somal chiasters 12-17 ^> ^^^^ a relatively large centrum about 

 6 /* ; usually with six actines with spinous truncate ends. 



Choansomal asters 35-45 m in diameter, with centrum about 

 5 M ; usually with 6 or 7 actines, truncate, bent at the extremity, 

 and with rough surface. 



Locality E. — Cone Point, Natal, 34 fms. ; bottom, broken 

 shells. 



There are three specimens, the two smaller being oval with 

 their long diameter, 4 and 6 cm. ; the largest specimen, which 

 is spherical, is 7 cm. in diameter. The new species belongs to 



