186 



COMPARATIVE ANATOMY. 



occupy the extreme end of the body. Each opens into a short 

 excretory duct, which is directed forwards, and is continued for 



some distance on the surface of the body ; it is 

 often found distended with spermatozoa, and so 

 functions as a seminal vesicle. According to 

 the extent to which their contents are developed 

 f&Jfll the ovaries project more or less into the coelom. 



y ■ They pass from before backwards, and open to 

 the exterior by a short and projecting tube, with 

 which a receptaculum seminis, placed beside the 

 ovary, is connected. 



§ 152. 



The generative organs of the Acanthocephali 

 are very peculiar, a higher stage of development 

 being implied by the separation in them of the 

 sexes. A chord (ligamentum suspensorium) tra- 

 versing the anenterous coelom carries seminal 

 organs in the male, and ovarian organs in the 

 female. The testes are two rounded glands, 

 which lie one above the other; a vas deferens 

 passes off from each of them to the posterior end 

 of the body, where it opens, in company with a 

 number of tubular glands, into the copulatory 

 organ. This consists of a sucker-like structure, 

 in the centre of which lies a conical process — 

 the true penis. This apparatus can be protracted 

 and retracted. In copulation it embraces the 

 similarly-shaped posterior end of the female's 

 body. The ova are developed in an ovary (o) 

 which accompanies the chord-like axis (Fig. 90, s), 

 and is either placed on, or is partly enclosed by, 

 it. The ova escape into the coelom, and are 

 taken up by the mouth of a wide bell-shaped 

 organ (g), which projects inwards from the hinder 

 end of the body, and leads into the short uterus, 

 which opens externally by a narrow vagina. 



Uy 



Fig. 90. Posterior 

 portion of the female 

 generative organs of 

 Echinorhynchus. 



Ovary, s Ligamen- 

 tum suspensorium. 

 g Bell-shaped organ. 

 £ Funnel, t 1 Terminal 

 portion of the ovi- 

 duct. The arrows 

 indicate the course 

 taken by the ova, as 



1 hey pass to the ex- 

 terior (after Greeff). 



§ 153. 



In the arrangement of their generative organs 

 the Hirudinea closely resemble the Platyhelmin- 

 thes, and especially the Trematoda and Turbel- 

 laria dendrocoela. This does not apply only to 

 their hermaphroditism, but to the double cha- 

 racter of their germ-glands, which are ordinarily arranged symmet- 

 rically ; and also to the position of the orifice of the whole system, 

 which is placed in the ventral median line. The position of the 

 male genital pore in front of the female is a repetition of the 



