23^ Records of the Indian Museum. [Vol. IX, 



resemble them in every respect except that they are smaller and 

 relatively more slender, their corresponding average measurements 

 being OT36 mm. by 0*004 mm., and that they show a greater 

 tendency to irregularity, a considerable proportion of them being 

 either somewhat sinuous as a whole or else bearing a globular 

 swelling in the middle, or exhibiting both peculiarities. 



Gemmules. — The gemmules form a pavement-layer which ad- 

 heres to the shell by means of a basal membrane and of the cage 

 of macroscleres in which they are included. Each has a single 

 straight bottle-shaped vertical tubule in the middle of the upper 

 surface, which is usually free to some extent from the investing 

 macroscleres. The cellular pneumatic layer is thick and well deve- 

 loped and its polygonal compartments are large and distinct. 

 The gemmule-spicules form a single somewhat irregular layer which 

 lies on and near the surface of the pneumatic layer; some spicules 

 being entirely, others partially embedded in it, and some lying on 

 the surface. 



Type. — No. Z. E. V. 6034/7 ^^^' Mus. (microscope-slide). 



Habitat. — On shell of Aetheria caillaudi from the Nile, 



This sponge is an interesting one as it is intermediate between 

 the widely distributed SpongiUa carteri of Asia, E. Europe, Mauritius 

 and possibly tropical Africa and my own 5. ambigua from S. Africa, 

 resembling the former in the shape of its gemmule-spicules and 

 the latter in the structure of its gemmules. It is one of the very 

 few Spongillidae that have smooth amphioxous microscleres. 



Together with the gemmules of S. aetheriae were others 

 belonging to a species of Stratospongilla or Corvospongilla (more 

 probably the latter) which the new species had evidently over- 

 whelmed by its growth. These gemmules and their spicules re- 

 semble those of C. bimnanica (Kirk.), but I cannot find a single 

 macrosclere or free microsclere other than those of 5. aetheriae 

 associated with them. It is evident that they represent neither 

 C. loricata, Weltner, which was originall}^ found on a shell of the 

 same genus, nor C. scabrispiculis, which is described below. 



Statoblasts of Plumatella occur in considerable numbers on 

 the shell on which the type of 5. aetheriae were found, and also the 

 remains of a Ctenostomatous polyzoon probably belonging to the 

 genus Hislopia, which has not hitherto been recorded from Africa 

 although it is widely distributed in Asia. 



Corvospongilla scabrispiculis, sp. nov. 



Sponge. — The external form, etc., of the sponge is unknown. 

 It encrusted shells of a mollusc of the genus Aetheria and was 

 apparently hard but friable and of a dark colour. A stout basal 

 chitinous membrane is present. 



Skeleton. — The only part of the skeleton that can be described 

 is the basal part. The structure of this is that of a stout network 

 formed of spicules enclosed in a chitinous membrane continuous 



