ROSEN, STUDIES ON THE PLECTOGNATHS. 



3 



forms a reservoir ofair. It would then, of course, beprobable 

 that a dilatation of the alimentary canal took place for this 

 purpose, but such is not the case. The slightly greater width 



Fjg. 1. Lactoplirys trigonus L. oes oesophagus; 

 st stomach; per peritoneum; i duodenum. 



that the stomach shows when compared with the duodenum 

 or the oesophagus has of course nothing to do with a dilatation 

 for the purpose of retaining the air. 



Fig. 2. a Triacanthus; b Monacanthus setifer; c Monacanthus trossulus; 

 d Tetrodon rubripes. (After Thilo.) 



Triacanthus. Thilo states about this fish, p. 77: »Tria- 

 canthus hat einen kurzen, nur wenig gewundenen Darm, 

 welcher vom Schlund bis After iiberall fast ganz gleich breit 

 ist.» Fig. 2 a shows a diagrammatical copy of Thilo's figure. 



