X24 s. GOTO. 



a few sections (each = 0.01 nun.) beliind, and on either side of, the 

 genital pore (PI. XV, fig. 1). The opening is ^vholly naked, and 

 leads into a long canal, the vaginal canal, Avhich proceeds just on 

 the inner side of, and parallel to, the intestinal trunk, and finally 

 opens into the f()re end of the ])aired yolk-ducts. The vaginal 

 canals are at first nearly of a uniform calibre, but very gradually 

 become larger as they approach the yolk-ducts. In Calicotijh' the 

 vaginal openings lie nearly midway between tlie median line and the 

 lateral margins of the body, nearly on the same level Avith the middle 

 of the uterus. Tlie vaginal canals, the terminal halves of which have 

 a smaller calibre than the others, ])roceed at riu'ht ano'les to the loni»' 

 axis of the body towards the median line, where tliey imite with each 

 other, and form a single duct, which then opens into the seminal 

 receptacle from the antero-dorsal side (PI. XIX, fig. 1). 



In all the species oi MlcrocoiijJc and Axhic I have examined, the 

 vao-inal openini»' is sini>-le, and is situated in the median line on the 

 dorsal side of the body. In most species of MicrocoitjJc the vagina is 

 Avhollv naked, but in J7/c'. rcticuldta (PI. V, fig. 5) and in Axluc 

 heterocrrca and A. aWrrans (PI. \\\, figs. ,") c<:, (); PL VIII, fig. 4) its 

 cavitv is armed with numerous, conical, chitinous s[)ines, which ai'e seen 

 in sections to l)e formed by simple elevations and ti'ansf >rmaiion of the 

 direct continuation of the investing membrane of the body (PI. ^^, 

 fig. 5; PI. A III, fig. 4). Moreover in all these s[)ecies the mesen- 

 chyma around the vagina is modified into a very com])act connective 

 tissue consisting of closely reticulated fibres, the interspaces of which are 

 filled with an exceedingly refractive substance, which i-emains wholly 

 unstained either with borax-carmin or haematoxylin (PI. \\, fig. 5 ; 

 PI. VII, fig. 5 ; PI. Vin, fig. 4). Again, in most si)ecies of Micru- 

 cotyh the vaginal opening leads into a single median canal of different 

 length according to the species, which usually proceeds straight back- 



