28 



ON CLASSIFICATION. 



The -principal ganglionic mass is situated behind and below 

 the mouth, in the re-entering angle between the gullet and the 

 rectum ; in other words, the intestine has, as in the Polyzoa, a 

 neural flexure (Fig. 9). In all Brachiopoda which have been 



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carefully dissected, a singular system of cavities and canals situ- 

 ated in the interior of the body, but in free communication with 

 the surrounding medium, has been discovered. This, which I 



