Manchester Memoirs, Vol. xlviii. (1903), No. 4. 3 



The accessory vesicle has glandular walls, and doubtless 

 correlated with its presence is the fact that uterine vesicles, 

 such as are found so commonly in the Cotylea, are never 

 found developed in connection with a vagina of the second 

 t)'pe ; Stylodioplana nationalist, mentioned above which has 

 a vagina of the first type, supplies an interesting example 

 of this correlation. It is the only Acotylean species 

 possessing uterine vesicles with which I am acquainted. 



It is conceivable that the accessory vesicles may dis- 

 appear altogether, and that a vagina of the first type may 

 be produced secondarily. This reduction seems to be in 

 progress in the genus Leptoplana. 



The lower part of the vagina of the second type is 

 sometimes very muscular, and may form a well-developed 

 bursa copulatrix as in Planocera and some species of 

 Leptoplana 



The uteri invariably open into this type of vagina 

 from below and on its morphologically posterior side. 



Turning now to the male apparatus it is found to 

 consist normally of a muscular vesicula seminalis ; of a 

 muscular conical penis which maybe armed with a stylet, 

 which communicates with the vesicula seminalis by 

 means of a ductus ejaculatorius or vesicular duct, and 

 projects into a chamber opening to the exterior, called the 

 antrum masculinum ; and lastly of a prostate gland with 

 muscular walls. Here again it is possible to distinguish 

 two types of the normal apparatus, to one or other of 

 which the majority of genera may be referred. The 

 means used to distinguish these two types are found in 

 the characters presented by the prostate gland. 



In THE FIRST TYPE^ the prostate is distinct from 

 the vesicular duct, and has a duct of its own, which 



1 This species should perhaps be made ihe type of a new genus. 

 "^ See Fig. 2, p. 7. 



