58 BULLETIN 66, UNITED STATES NATIONAL MUSEUM. 



and consisting of a short gullet, passing into an oesophagus, which 

 dilates into a crop. Thence it is greatly extended as the stomach 

 and terminates in the very short intestine. At about the fourth 

 instar the gullet lies nearer the ventral surface of the head as a short, 

 somewhat flattened tube, coated inside with chitin. The walls are 

 lined with strong muscles, circular, longitudinal, and others directed 

 to the walls of the head. The longitudinal muscles pass along the 

 dorsal side only. Four dorsal muscles distend the gullet and are 

 directed sideward and forward, being counteracted by two of the 

 more numerous ventral muscles, which extend sideward and back- 

 ward. A large number of fibers extend forward to the anterior region 

 of the head. The cesophagus has a very slightly developed longitudi- 

 nal and circular musculature, and on its external surface bears numer- 

 ous one-celled glands, probably salivary. The crop is expanded cone- 

 shape posteriorly, its walls consisting of cylindrical epithelium coated 

 inside with chitin. On the outside a continuation of a weakly devel- 

 oped muscular layer from the cesophagus is observed. As the larva 

 develops the gullet expands and the crop contracts, no longer form- 

 ing a separate section. The stomach, or middle intestine, extends 

 from the second thoracic to the eighth or ninth abdominal, but is not 

 distinctly demarked from the crop. At its beginning the stomach is 

 somewhat narrowed. Then it forms a cylindrical tube, which is 

 strongly narrowed posteriori}^, ending blindly. The musculature is 

 very slightty developed and consists of ramified fibers sparsely situ- 

 ated on the surface of the stomach in the slightly developed mem- 

 brane of connective tissue. The epithelium consists of very large 

 cells, which stand out into the cavity of the intestine in the form of 

 hemispheres, or sometimes flask shaped, narrowed at base. Each 

 cell has large-grained protoplasm with nucleus and nucleolus, and is in 

 texture fibrous to reticulate. As the larva develops smaller cells arise 

 at the bases of these large cells, also bearing nucleus and nucleolus. 

 The large cells dwindle, disintegrate, and finally drop out into the 

 intestine. At the same time the small cells increase. In the pupal 

 stages none but minute cells remain. The posterior intestine is very 

 short and of very simple structure. At the first it has a conical form, 

 is somewhat flattened from the ventral side to the dorsal, and opens 

 outside on the dorsum of the last segment with an anal opening in 

 the form of a transversal slit. Its walls consist of cylindrical epithe- 

 lium and are coated inside with chitin. Toward the end of the 

 larval life the intestine somewhat increases in length and assumes a 

 cylindrical form, slightly narrowed at the anterior end. It is cylin- 

 drical in the pupa also (Nassonow, 1892 e, pi. 1, fig. 23; pi. 2, figs. 

 1, 2, 4, 6). 



In the female the canal has at first the same structure as that of the 

 male. It later differs by the intestine becoming atrophied and the 



