562 



N. Annandale. 



description is not oiily incomplete biit actually raisleading, owing to 

 this paucity of material, and I therefure take tlie opportunity to 

 publish a more detailed account of a form which runs a considerable 

 risk of being- described as a new species, seeing that it occurs both 

 in Asia and Africa. I have had before me in drawing- up this new 

 description several of tlie original gemmules, a number of specimens 

 obtained by myself in a lake in the Bombay Presidency, and also 

 a considerable amount of material collected by Prof. Webee in 

 Natal. 



SpongiUa homhayensis may be described as follows: 



Sponge formiiig a ratlier thin layer on solid objects; its surface 



irregulär; the oscula and pores inconspicuous; the subdermal space 



small. The skeleton, owing to the large number of spicules. compact, 



but incohereut and almost amorphous; vertical spicule-fibres present 



Fig. B. 



Gemmiile spicules of S. bomhayensis. 



a From type specimens (Bombay). 

 b From specimeu from Natal. 



Fig. C. 



Spicules of S. bombayensis from Natal. 



a Skeleton spicules. 

 b Free microscleres. 



in places but practically devoid of spongin; a more or less definite 

 reticulation of horizontal spicules lying immediately under the 

 membrane, which they rarely penetrate. Skeleton spicules (megascleres) 

 slender, short, amphioxous, smooth, slightly roughened, or irregularly 

 and very minutely spined, straight or feebly curved. Free spicules 

 (microscleres) slender, short, sharply amphioxous, straight or nearly so, 

 irregularly roughened or minutely spined all over the surface, scanty 

 in the parenchyma, abundant in the membrane. Gemmule spicules 

 Short and rather stout, very variable in proportions, abruptly pointed 

 or amphistrongylous, sometimes inflated in the middle, irregularly 

 roughened or minutely spined all over. Gemmules very variable in 

 size, round or oval, generally flattened at the base, firmly adherent 



