188 HUGH WATSON. 



THE REPEODUCTIVE ORGANS. 



The genital or reproductive organs of Apera are of a 

 simple generalised type^ at least so far as their external 

 structure is concerned (PL XXIII, figs. 143, 144, 146-149). 

 As up to the present only a very few fully mature specimens 

 have been collected, I have thought it advisable to preserve 

 the reproductive organs of these almost intact, and not to cut 

 them up in order to examine their histology. The following 

 account, therefore, deals chiefly with the external morphology 

 of the genital system. The reproductive oi-gans of Apera 

 purcelli are unknown, the only dissected specimen being 

 immature. 



The Hermaphrodite and Female Organs. — The herma- 

 phrodite gland or ovotestis is partially embedded in the 

 right side of the posterior division of the liver (see especially 

 PI. IX, fig. 31). It is a racemose gland composed of a 

 cluster of oval or pear-shaped follicles. These follicles are 

 smallest in Apera burnupi and A. sexangula (PL XXIII, 

 figs. 148, 149). In the other species they are larger and 

 tend to be fewer in number, until in A. parva the entire 

 hermaphrodite gland consists of only about four follicles 

 (fig. 146). The very slender ducts from the different follicles 

 unite to form the hermaphrodite duct, which is long", and 

 usually more or less convoluted and slightly swollen towards 

 the middle of its length, especially in A. dimidia. But the 

 convolution is not so pronounced as in many other genera. 

 In front the hermaphrodite duct becomes embedded in the 

 albumen gland. At the extreme anterior end it is swollen 

 so as to form a minute spherical vesicle, which is doubtless to 

 be regarded as a rudimentary vesicula seminalis. 



The albumen gland varies enormously in size according 

 to the exact state of maturity of the individual (cf. PL IX, 

 figs. 27, 31). In some specimens it reaches a very large size 

 indeed (PL XXIII, fig. 144). The common duct, or ovi- 

 spermatoduct, is very long and much convohited and twisted 

 in Apera burnupi and A. sexangula (PL XXIII, figs. 



