Medicinal Leech. 219 



of these terminal coeca is much larger than that of the 

 segment of the dig'estive tube which lies between them, 

 and which further differs from the homologous segment in 

 the Horse-leech, in not possessing an}^ lateral sacculations. 



d I . The most anteriorly placed of the nine testes of either side, 

 communicating by a short transverse duct passing outwards, 

 with a common vas deferens, which receives posteriorly the 

 secretion of the eight posterior testes, and anteriorly leads 

 into a convoluted epidymis-like vesicula seminalis, which is 

 seen in this figure in the space bounded by the lines lettered 

 i andy. 



dz. Last testis of right side. The segments between this one 

 and the most anterior of the genital segments /, have their 

 cutaneous glands greatly enlarged at the time of ovi- 

 position, and secrete the external chitinous shell of the 

 * cocoon^ in which the eggs are lodged ; whilst the glands 

 of the female generative apparatus secrete the albuminous 

 matter which fills the shell and surrounds the eggs. 



d^. Sixth testis, displaced outwards so as to show its own con- 

 nection with the vas deferens, and the relation of apposition 

 with it, into which a coecal process from one of the seg- 

 mental organs, e 2, comes. 



ei. Segmental organs consisting of one portion, which is tu- 

 bular and loop-shaped to the naked eye, but so mutually 

 inter-communicating when examined with the microscope 

 as to be really labyrinthiform ; of a second j)ortion, which 

 is vesicular and opens on to the exterior ; of a third, which, 

 as a slender but resistent duct, connects the loop-shajjed 

 with the vesicular portions; and, in the eleven posterior 

 segments, of a fourth portion, in the shape of a coecal 

 process, which is prolonged inwards in the two most pos- 

 terior up to the nerve-cord ; in the ante-penultimate up to 

 the vas deferens from the last testis ; and in the eight 

 others up to the eight anterior testes. 



e 2. Segmental organ, shown with all the four constituent por- 

 tions just mentioned; the testis with which its coecal 

 process comes into apposition, though not into any tubular 

 continuity, having been displaced outwards. The vesicular 

 part of the segmental organ lies in every case posteriorly 



