530 



JBORTT-FIFTH REPORT ON THE STATE MUSEUM. 



The Nervous System. 



The nerve-collar surrounding the oesophagus constitutes the 

 principal nerve mass in the Brachiopoda. In the articulate 

 species there is a large ganglion (suboesophagian) on one side of 



Fig. 188. 



(Esophageal ganglion of Magellania cranium. 



(Hancock.) 



the oesophagus, connected by fine lateral commissures with a 



smaller ganglion on the 

 opposite side. In the inar- 

 ticulates (Lingula, Crania) 

 so far as ascertained, the 

 upper and lower ganglia 

 are not so well developed, 

 the nerve-ring being of more 

 equal size throughout. 

 From the swellings of the 

 oesophageal rings, nerve- 

 fibers are given off to the brachia, muscles, and the two lobes of 

 the mantle. It would appeal- that the nervous system as a whole 

 is more highly developed in the articulate than in the inartieulate 

 bracbiopods. \\\ has not been demonstrated that the adult 



82 



Fig. 189.— Nervous system of Crania. <e, oesopha- 

 gus in section; c, collar; a, cerebroid ganglion; n, 

 brachial nerve; e, subcesophageal ganglion ; g, inferior 

 nerve; p, dorsal pallial nerve; p, ventral pallial nerve; 

 m, nerve of muscles. (Joubin ) 



