34 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 89 



discharge a substance for attaching the eggs to a support, or for 

 aggkitinating the eggs to one another, but the secretion may also be 

 used to form an egg covering, or an egg capsule, and in the stinging 

 Hymenoptera one of the glands produces an irritant or toxic liquid. 

 In some insects the accessory glands are absent, and their function 

 may be assumed by special glandular parts of the oviducts. 



The median oviduct and the spermatheca have no homologues in 

 the male insect ; but it seems possible, as some writers claim, that the 

 male ejaculatory duct and mucous glands are derived from the same 

 invagination of the ninth segment that forms the accessory glands of 

 the female. 



The oviductus communis, in all insects but Dermaptera, becomes 

 extended posteriorly. In most insects the definitive opening of the 

 median oviduct (fig. 8 B, Ode) is carried back to the posterior part of 

 the eighth segment, and comes to lie just before the opening of the 

 spermatheca (Spt) behind or above the eighth sternum. 



Insects having the aperture of the definitive egg passage situated 

 on or behind the ninth abdominal segment include some species of 

 Hemiptera, Parnorpidae, and Diptera, most Trichoptera, and all 

 Lepidoptera and Coleoptera. An opening on the eighth segment in 

 conjunction with that on the ninth is retained in most adult Lepi- 

 doptera, and, as we have seen, occurs in immature stages of Coleop- 

 tera. A similar opening on the eighth segment is present also in species 

 of Cicadidae in which the genital chamber opens posteriorly on the 

 ninth segment. The trichopterous families Limnophilidae and Phry- 

 ganiidae preserve the more primitive condition in that the female 

 genital aperture is on the eighth abdominal segment just behind the 

 eighth sternum. In Panorpa the oviductus communis, the sperma- 

 thecal duct, and the duct of the accessory glands discharge into an 

 open cavity in the ventral part of the ninth segment. This cavity is 

 a simple invagination of the body wall widely open laterally and 

 posteriorly above and behind the edges of the somewhat enlarged 

 sternal plate of the ninth segment, and its lumen corresponds with the 

 genital chamber of more generalized insects, though it is closed below 

 by the ninth sternum. The anus of Panorpa lies on the ventral surface 

 of the very small eleventh segment of the female. In trichopterous 

 forms having the female genital aperture behind the ninth sternum, 

 the oviduct, the spermatheca, and the accessory glands open likewise 

 into a common chamber, but the latter is here entirely enclosed within 

 the body, and has a small aperture at the base of the terminal (tenth) 

 segment in common with the rectum. In Coleoptera the part of the 



