THE STRUCTURE AND METAMORPHOSIS OF THE 

 FORE-GUT OF CORYDALIS CORNUTUS L. 



ROBERT MATHESON 

 From the Entomological Laboratory, Cernell University 



TWENTY-NINE FIGURES 



Owing to the large amount of work that has been done and is 

 still being done on the metamorphosis of the more specialized 

 insects it has seemed advisable to make a careful survey of some 

 generalized form. It was with this object in view that the pres- 

 ent work, though dealing with a restricted region, was undertaken. 

 The writer hopes to continue these studies as time permits. 



The present subject was suggested by Prof. W. A. Riley and 

 the work was done under his immediate supervision. To Pro- 

 fessors W. A. Riley and J. H. Comstock I wish to extend my 

 thanks for advice and criticism. 



STRUCTURE 



The fore-gut of Corydalis extends as practically a straight, 

 narrow tube from the mouth to the middle of the second abdomi- 

 nal segment where it joins the mid-intestine (fig. 1). There are 

 but two slight enlargements, one at the anterior end, the pharynx, 

 and a more considerable one near the posterior end, the gizzard 

 (fig. 1, ph. and k). The caudal end projects into the mid-intestine 

 to form a characteristic oesophageal valve. Morphologically it 

 may be divided into five well marked regions : pharynx, oesopha- 

 gus, gizzard, the region between the gizzard and oesophageal 

 valve, and the oesophageal valve. Along each side of the fore- 

 intestine runs a branch of the visceral nervous system (fig. 1, n) 

 while various branches of the tracheal system furnish the neces- 

 sary air supply. 



581 



JOURNAL OF MORPHOLOGY, VOL. 23, NO. 4 

 DECEMBER 1912 



