90 SILICEOUS SPONGES. 



Khopalospongia geegaeia, Benett, sp. (Plate XXII. figs. 2, 2 «, 2 J, 2 c.) 



1831. Pohjpothecia gregaria, Benett, Cat. Org. Rem. County of Wilts, t. 14. 

 1847. Non Jerea gregaria, Michelin, Icon. Zooph. p. 134, t. 38. f. 1. 



Sponges elongate, club-shaped, with rounded conical summits, either simple or 

 growing in groups of three or four individuals of different sizes, closely attached by 

 their lateral surfaces. Rarely, also, two individuals possess a common stem. The 

 outer surface of the body, or club-shaped portion, is either smooth and evenly 

 rounded, or with irregular nodose projections, or covered with small pustular 

 elevations. The cylindrical stem frequently exhibits parallel longitudinal furrows ; 

 it appears to have given off root-like processes at its termination. Small individuals 

 measure 55 mm. in height and 14 mm. in width ; whilst a large example is 300 mm. 

 in length by 45 mm. in width. 



The outer surface of the sponge is thickly covered with canal-apertures from '5 to 

 •75 mm. in width. These canals apparently extend in an arched direction towards 

 the centre of the sponge ; in a transverse horizontal section only a few of the larger 

 canals are distinguishable. Both in vertical and horizontal sections distinct lines of 

 growth parallel with the contour of the sponge are exposed. 



The spicular mesh is relatively close ; the smooth arms of the regular spicules are 

 •06 mm. in width, whilst the tuberculated arms measure •OS mm. wide. The regular 

 spicules are indiscriminately mingled with the others ; they appear, however, to be 

 more frequent in the central portion of the sponge, whilst the irregular tuberculated 

 spicules prevail nearer the outer surface. Interior canals are preserved in many of 

 the spicules. This species is not uncommon in the Upper Green Sand. 



There can be no doubt that Miss Benett's figure represents this species, particularly 

 as there is no other sponge from the Green Sand with a corresponding form. Michelin 

 has referred this species to his Jerea gregaria, with which, however, it has no near 

 affinity. 



Distribution. Upper Green Sand : Warminster and vale of Pewsey, Wiltshire. 



Rhopalospongia obliqua, Hinde, n. sp. (Plate XXII. figs. 3, 3 a.) 



Sponge compound, consisting of two short individuals, inversely conical in form, 

 growing from a single short, somewhat compressed stem. The summits are appa- 

 rently oblique. 



A transverse section exposes the canals, 1 mm. in width, which extend to the outer 

 surface. These canals are more numerous and distinct than those of the last species. 



The spicular structure of the interior resembles that in B. gregaria. 



I have only met with a single example of this species : it is 85 mm. in height and 

 51 mm. in width. 



Distribution. Upper Green Sand : Warminster, Wilts. 



