264 ANATOMY AND PHTSIOLOGT 



Fl8. 



— . Cylindrical : entirely spined ; spines ot the 

 middle cylindrical, those of the terminations 

 CONICAL AND RECURVED. — These spicula might 

 readily be mistaken by a hasty observer for those 

 of Spongilla alba, but a closer observation exhibits 

 essential differences in their mode of spination. 

 They are very numerous in the envelope of the 

 ovary of Spongilla cinerea. Carter, from the water- 

 tanks of Bombay. They are so nearly of the same 

 form as those represented by Fig. 207, as to render 

 it unnecessary to figure them. Page 59. 



2nd. Spicula disposed in lines radiating from the 

 centre to the circumference of the ovary. 



Birofulate and Boletiform Spicula. 



208. Adult recurvo-dentate birotulate spiculum. 



Shaft entirely spined, from the ovary of Spongilla 

 plumosa. Carter. X 660 linear. Pages 59 — 

 61. 



209. A view of the inner surface of one of the rotulse of 



the spiculum represented by Pig. 208, showing the 

 amount and irregularity of the dentation of its 

 margin. X 660 linear. 



210. First stage of development of a birotulate spiculum 



hoxa.^QQy9x^ d Spongilla plumosa. Carter. X 660 

 linear. Page 61. 



211. Second stage of development of a birotulate spiculum 



from the ovary of Spongilla plumosa. Carter. X 660 

 linear. Page 61. 



212. Third stage of develepment of a birotulate spiculum 



from the ovary of Spongilla plumosa. Carter. X 660 

 linear. Page 61. 



