90 Annals Entomological Society of America [Vol.1, 



in size. The tip of the egg-tube passes over gradually into the 

 terminal chamber, which, in turn, passes over into the terminal 

 filament. 



A histological study of the wall of the egg-tube shows that it 

 is covered externally by a peritoneal membrane, in which anas- 

 tomosing, transversely-striated muscle fibres are embedded. 

 Toward the distal end of the ovariole, the peritoneum is especially 

 well developed, while posteriorly it gradually becomes thinner. 

 The anastomosing muscles extend to the apex of the ovariole, 

 being present in even the terminal filament. Within the peri- 

 toneum is a basement-like membrane ; this membrane is sometimes 

 distinctly visible between the nutritive and egg-chambers. 



Oviduct and Oviductus Communis: In general, the histological 

 structure of the oviduct will hold good also for the oviductus 

 communis anterior to the spermatheca. The following layers, 

 passing from within outward, are present : (i) a chitinous intima ; 

 (2) an epithelial layer; (3) a longitudinal muscle layer; (4) a cir- 

 cular muscle layer; and (5) a peritoneal membrane (Fig. 5). 



When no eggs are present in the oviduct or oviductus commu- 

 nis, their wall is thrown into folds which are nearly filled with 

 longitudinal muscles (Fig. 5, In^. The chitinous intima varies 

 but little in thickness throughout the entire genital duct; such 

 variations as occur are found directly beneath the egg-tubes, 

 where the chitin is extremely thin and hardly perceptible. A 

 surface view of this intima shows the presence of long, yellowish, 

 chitinous bristles which are not distributed uniformly, but are 

 clustered in groups (Figs. 3 and 5, b). The epithelial cells, with 

 cell boundaries usually indiscernable, contain a large ovoid 

 nucleus embedded in a slightly granular cytoplasm. External 

 to the epithelial layer are the longitudinal muscles, which are 

 somewhat better developed than the circular muscles just outside 

 of these. 



Spermatheca: A longitudnial section through the sperma- 

 theca show^s that the structure of the chitinous intima is some- 

 what similar to the chitinous integument which Folsom (16) 

 described for most insects. He writes : ' ' The chitinous integument 

 (Fig. 88) of most insects consists of two layers: (i) an outer layer, 

 homogeneous, dense, without lamellae or pore canals, and being 

 the seat of the cuticular colors; (2) an inner layer, 'thickly 

 pierced with pore canals, and always in layers of dift'erent refrac- 

 tive indices and different stainability.' (Tower.) These two 



