VIII 



PHYLUM MOLLUSCOIDA 



373 



evidently homologous with the foot-segment of the larval Brachio- 

 pod. The end of the body of the Brachiopod from which the 

 peduncle proceeds is thus the ventral portion. From the position 

 of the epistome and lophophore, it follows that the dorsal valve 

 of the Brachiopod, being on the same side of the mouth as the 

 epistome, lies on the side of the body corresponding with the anal 

 side of the Polyzoan, though the intestine is bent round in the 



B 



-tent 



FK;. 300. A, Diagrammatic median section of a phylactolsematous Polyzoan. an. anus ; 

 ep. epistome ; tp. cav. epistome-cavity ; funic. funiculus ; gang, ganglion ; int. intestine ; 

 mo. mouth ; neph. nephridium ; o's. oesophagus ; st. stomach ; tent, tentacles. B, diagram- 

 matic median section of Phoronis. mes. mesentery ; nr. nerve-ring. Other letters as in A. 

 (From Korschelt and Heider, after Cori.) 



opposite direction and directed towards the ventral valve. The 

 supra-oesophageal ganglion of the Brachiopod represents the single 

 ganglion of the Polyzoa, though it is subordinate in importance to 

 the infra-oesophageal ganglion not represented in the latter group. 

 Other important points of resemblance between the Brachiopoda 

 and the Phoronida are seen in the character of the nephridia and 

 the presence in both of larval forms which may very well be looked 

 upon as modified trochophores. 



