282 Animal Biology 



SPICULES 

 GASTRAL CAVITY 



-OSTIUM 



gjj^^g^^^RADlAL CANAL 



^^S y^ lNCURRENT CANAL 

 ^ PROSOPYLE 



APOPYLE 



Fig. 82. — Cross section of a sponge, Scypha (Grantia), somewhat diagram- 

 matic. The ostium is also known as the incurrent pore, the radial canals as the 

 excurrent canals, the prosopyle as the connecting canal (between radial and in- 

 current canals), the apopyles as excurrent pores. (From Parker and Clarke: In- 

 troduction to Animal Biology, The C. V. Mosby Co.) 



OscuJam 



.- — Sieve membrane 

 - - Spicule 



POKQ 



Fig. 83. — Leucosolenia, a small colony of a simple sponge of the class Calcarea. 

 In the upper right quarter the outside covering has been removed to show the 

 structures beneath. (See also Fig. 84.) 



