BY R. VON LENDENFELD, PH.D. 327 



The surface of the sponge is smooth, here and there smal 

 apertures with a circular circumference and a diameter of 0-1 inch 

 occur. These are slightly i-aised above the general surface of the 

 sponge, and more numerous towax'ds the tips of the finger-shaped 

 processes than in other parts. 



The base of the sponge adheres very rigidly to the oyster shell. 



The microscopic investigation reveals a skeleton, consisting of a 

 network of exceedingly slender, anastomosing threads, consisting 

 of dense masses of silicious spicules. 



The spicules are simple, rod-shaped, slightly bent and pointed 

 abruptly at each end, the outer apparently smooth surface is 

 pervaded by numerous pores closed externally by a sieve with 

 extremely fine perforations. 



These holes lead into extensive lacunose sub-dermal cavities 

 from whence canals originate, which extend in a centripetal 

 direction, and which continually ramify, supplying small ciliated 

 chambers situated in the interior. From these other canals 

 originate, which unite to form wide oscular tubes. 



It appears that five years ago this sponge did not occur in the 

 locality, that afterwards the sponges made their appearance and 

 killed the oysters thereon, and covered that area with a dense 

 growth of sponges, standing so close to one another, that there 

 was no room for the oysters between them. 



The most interesting fact however, is that now since all the 

 oysters have died out, the sponge is likewise disappearing, and 

 great patches of the bottom in that locality are already clean. 



It appears from the above that the sponge described, which I 

 have named Ghalimda Cooeii, grows on the shells of living oysters, 

 but disappears after the oysters are dead, and furthei', that the 

 sponge exerts some direct influence on the oysters, which is so 

 detriraentary to the latter that they die. 



There is certainly no direct connection between the oyster 

 animal and the sponge whatever, as the sponge only adheres to the 

 outer surface of the shell. 



