376 H. s. PRATT, 



and the production of spermatozoa to have begun. The testes are 

 two iu number; they are oval bodies, considerably larger than the 

 ovary, and lie side by side between that organ and the acetabulum, 

 towards the ventral side of the bodyiI(Pl. 25, Figs. 2 and 3, T). De- 

 licate vasa etï'erentia lead from the testes forward towards the hinder 

 end of the vesicula seminalis, in the immediate neighborhood of which 

 they join each other, forming the vas deferens. This duct immediately 

 expands into the vesicula seminalis, a large lenticular organ with a 

 diameter of 0.035 mm and a length of 0.06 mm which lies dorsad of 

 the acetabulum very nearly in the center of the body (PI. 25, B'igs. 2 

 and 3, v. sem.). It was filled with spermatozoa in all the animals in 

 which it came under observation. From its forward end the ejacul- 

 atory duct leads forward to the genital vestibule. The ejaculatory 

 duct may be divided into two portions, the pars prostatica or glan- 

 dular portion (PI. 25, Fig. 2, p. p.) and the narrow neck by which it 

 communicates with the genital vestibule (PI. 25, Fig. 2, n.). The first 

 named division is a long tube which passes forward dorsad of the 

 acetabulum, the last named is very short and serves to connect the 

 pars prostatica with the genital vestibule (PI. 25, Fig. 2, n); and this 

 organ, which is also a long tube of about the same length as the pars 

 prostatica, passes forward to the genital opening (PI. 25, Fig. 2, gen. 

 vest). The genital opening is situated on the ventral side of the 

 animal, beneath and just back of the outer rim of the oral sucker. 

 (PI. 27, Fig. 12, gen. op.) 



The finer structure of these organs presents but few peculiarities. 

 The cells composing the testes were in active proliferation, many 

 karyokinetic figures being seen in them. The vesicula seminalis is a 

 muscular sac whose walls are composed of parallel fibres which pass 

 spirally around it. The pars prostatica has likewise muscular walls, 

 longitudinal fibres being outermost and inside of these are circular fibres. 

 The lumen of the tube is bounded by an intima raised into papillae 

 which project into it (PI. 27, Fig. 13 p. p.), a peculiarity of structure 

 which is present in the adult Apohlema appendiculatum but is not 

 found in most members of the genus. Surrounding the tube are large 

 pear-shaped gland- cells; they are contained in no limiting membrane 

 but project free into the parenchyma. 



According to Looss (1896) it is the secretion of these gland-cells 

 which causes the formation of the papillae. The above described 

 portion of the ejaculatory duct is called by Juel (1. c.) and Monti- 

 CELLi (1891, p. 10), the cirrus or penis, but as Braun (1892, p. 707) 



