206 



Mr. W. S. Kent on the Relationshij) of 



Oscar Schmidt, that every part of the sponge-body which 

 possesses an excurrent orifice (osculiim) is to be regarded as a 

 distinct individual, he considers each single sponge-body 

 bearing only a single osculum, and which he denominates an 

 individual or person, to be the equivalent of an Actinia or 

 any other such solitary coral-animal — and this not only as far 

 as their distinct individuality is concerned, but also in regard 

 to their respective morphological characters. 



The accompanying diagrammatic illustrations of sections of 



Fig. 1. 









Fig. 1. Hypothetical vertical section of a Spongilla having a single 

 excurrent orifice : a, excurrent orifice ; h, central excurrent cavity ; 

 c, interstitial canal-system ; (/, ciliated chambers ; e, intermarginal 

 cavities ; /, incurrent apertures ; g, dermal membrane ; h, deeper sub- 

 stance of the sponge*. 



Fig. 2. Transverse section of a similar sponge j the lettering corresponds 

 with that made use of in the last figure. It is necessary to observe 

 that radiate symmetry has been greatly exaggerated in these two 

 figures to adapt them as far as possible for comparison with figs. 3 & 4. 



Fig. .3. 



Fig. 3. Ideal vertical section of an Actinia: a, the mouth ; b, alimen- 

 tary canal or cavity ; c, cojnmon digestive cavity ; d, intermesen- 

 teric chamber, or portion of perivisceral cavity ; e, a mesentery ; /, re- 

 productive organ ; .9, body- wall ; A, tentacles; t', wall of alimentary canal. 



Fig. A. Transverse section of the same, the lettering in correspondence 

 with the last. 



* Figs. 1 & 3 are modified from illu.strations given in Prof. Huxley's 

 * Introduction to the Classification of Animals.' 



