NO. 6 



GRASSHOPPER ABDOMEN — SNODGRASS 



35 



The circular muscles of the proctodaeum begin just behind the bases 

 of the Malpighian tubules, forming here a pyloric sphincter of large 

 fibers (A, B, c), and continue {d) uninterruptedly over the entire 

 length of the rest of the stomodaeal tube. They are particularly strong 

 on the colon. The longitudinal muscles arise as distinct fibers on the 

 anterior end of the proctodaeum in the neighborhood of the Malpighian 

 tubules, but the fibers immediately converge over the pyloric sphincter 

 into six equally spaced muscle bands (<?) on the wall of the ileum. 



E 





Eppt 

 29S 



Mai J\ 



Fig. i6. — The proctodaeum of Dissosfcira Carolina. 



A, general view of the proctodaeum, showing its subdivisions, its muscles, 

 and groups of Malpighian tubules given off from anterior end. B, internal view 

 of pyloric region between ventriculus and ileum, with pockets from which the 

 Malpighian tubules arise. C, anterior ends of rectal "glands," inner view of 

 rectal wall. 



a, b, circular and longitudinal muscles of ventriculus; c, pyloric sphincter; 

 Cln, colon; d, circular muscles of proctodaeum; e, bands of longitudinal procto- 

 daeal muscles ; Eppf. epiproct ; /, fold marking terminus of ventricular wall ; 

 g, Malpighian pockets ; h, i, internal folds of wall of ileum ; //, ileum ; /, rectal 

 pads ; Mai Malpighian tubules ; Py, pylorus ; Rect, rectum ; Vent, ventriculus ; 

 264, 286, 2go, ventral, dorsal, and lateral dilator muscles of posterior part of 

 rectum; 2^5, 296, epiproctial and paraproctial dilators of the anus (see fig. 14). 



and continue thus to the posterior end of the latter. Here each band 

 breaks up into a group of fibers branching on the colon, some of which 

 appear to go beneath the circular fibers to attach on the intima of the 

 proctodaeal wall. On the posterior part of the colon the longitudinal 

 fibers reassemble in six bands that traverse the outer wall of the rectal 

 sac, and then again branch and appear to go beneath the circular mus- 

 cles to be inserted on the wall of the terminal part of the rectum. 

 Finally the longitudinal fibers appear once more as six short external 

 bands on the terminal part of the rectum, and end with attachments on 



