A Sycon Sponge. 



A SYCON SPONGE 

 / 



(jGrantia s 



General Anatomy. Simple sponges, which have been 

 described under the name Grantia, are found associated 

 with Leucosolenia along the Atlantic coast. Specimens vary 

 considerably in size, the larger sometimes reaching one inch 

 in length. 



Examine a dry specimen with a lens and note the general 

 outline of the body, the somewhat expanded base, the ter- 

 minal osculum, surrounded by a funnel of spicules, and the 

 numerous incurrent pores t distributed over the external sur- 

 face of the body, and more or less hidden by the numerous 

 spicules. Are there buds attached to the sponge body? 



Make a drawing illustrating the above points of the exter- 

 nal anatomy. 



With a sharp scalpel open the sponge by making a longi- 

 tudinal stroke from base to osculum. The central cavity or 

 cloaca will be exposed, and its walls will be found pierced 

 with numerous openings, the gastric ostia. Note that the 

 cut edges, much thicker than in Leucosolenia, are traversed 

 by parallel tubes, those entering the central chamber through 

 the gastric ostia being called radial canals, while the shorter, 

 which enter from without through the incurrent pores, are 

 called the incurrent canals. The incurrent canals commu- 

 nicate with the radial canals through certain small openings 



