148 Psyche [October 



into the cavity, forming the pregenital tube (tg. + mt.+is.); at the 

 apex of this tube, where the testicular threads are attached, 

 another invagination takes place forming the ejaculatory duct 

 (lb, 2). At the base of the pregenital tube of R. ohscurus a fold 

 arises which developes into the tegmen (Ic) ; the tube lengthens by 

 the apex growing into the cavity of the invagination and the base 

 through the tegminal fold, into the body cavity (Id). A constric- 

 tion round the middle of the pregenital tube divides it into two 

 portions, the apical portion forming the internal sac and the basal 

 the median lobe (3), As the internal sac increases in length it 

 lies crumpled up within the invagination and is not withdrawn 

 into the median lobe until after the imago is fully developed (4). 

 In Lamellicorns and Staphylinids I have also observed that the 

 internal sac is. not withdrawn into the median lobe until the imago 

 is fully developed. 



From each side of the base of the median lobe a long invagination 

 of the ectoderm takes place, these become highly chitinized and 

 form the median struts: at first broad, more like those in Ceram- 

 bycidoe, they afterwards become slender. From a medio-ventral 

 point on the tegminal fold arises a larger invagination which also 

 becomes highly chitinized (along with the tegminal fold) and forms 

 the tegminal strut (le). From a point on the anterior wall of the 

 genital invagination a slender invagination takes place, grows 

 round to the right side, becomes chitinized and forms the spiculum 

 (3, 4, sp.). The basal portion of the walls of the genital invagina- 

 tion becomes chitinized (4a) and, together with the membranous 

 apical portion (4b) attached to the tegmen, form the second con- 

 necting membrane. If the oedeagus be dissected out of a half or 

 three fourths developed pupa and placed in acetic acid, so as to 

 cause the cells to swell up, the true nature of the folds and invag- 

 inations forming the tegmen, tegminal and median struts and 

 spiculum will be observable. 



Lateral lobes are outgrowths from the tegminal fold. In 

 Carpophilus humeralis they at first form two large rounded lobes, 

 eventually growing to the pointed processes found in the adult. 

 (5). In the same insect the internal sac, which is exceedingly 

 long, first grows to the mouth of the genital invagination and then 

 grows into the body cavity; the flagellum at first is a short thick 

 process (5 fg) and lengthens with the internal sac. 



