292 Ajinals Eatoinological Society of America [Vol. XI. 



rower and more elongate, passing almost imperceptibly into the 

 type characteristic of the mid-intestine. 



The transition area is shown in figure 9. 



Basement membrane. The basement membrane is continuous 

 from the crop to the ventriculus. 



Imaginal ring. There is no clearly defined imaginal ring. 

 The cells on the extreme posterior face of the oesophageal valve 

 are very small and close together, and probably constitute 

 the imaginal ring of the fore-intestine. This is very com- 

 parable to the conditions described by Poyarkoff (1909, 1910) in 

 the elm leaf beetle, where the imaginal mid-intestine is derived 

 from the cells of the posterior face of the larval oesophageal 

 valve, although these cells are not sharply separated off as a 

 distinct imaginal ring in the larva. The cells are never crowded 

 together in AUica so as to form an apparently several layered 

 imaginal ring, as in the case in Cybister (Deegener 1904), where 

 the ring lies above the oesophageal valve. 



Longitudinal miiscles. The longitudinal muscle fibres are 

 continuous from the fore-intestine into the mid-intestine. With 

 respect to the connective tissue sheath in which the circular 

 muscles lie, they are internal in the fore-intestine, but at the 

 point of junction between the crop and the ventriculus, each 

 fibre divides into two or three smaller ones which penetrate 

 this sheath, so that the longitudinal muscles lie outermost 

 in the mid-intestine. There are about twenty of these fibres 

 in the fore-intestine, and about forty at the anterior end of the 

 mid-intestine. 



The passage of these muscles from the crop to the ventriculus 

 is shown in figure 10. 



Circular muscles. The circular muscles of the fore-intestine 

 and the mid-intestine appear to be continuous, since they both 

 lie in the same connective tissue tube around the intestine, but 

 doubtless- here, as in all insects in which the conditions have 

 been studied, embryologically they have very different origins, 

 and are not homologous. The muscles immediately at the 

 junction form a strong sphincter. 



