88 STERELMINTHA. 



other nervous filaments arise to supply the suckers, and the 

 anterior part of the body. 



The organs of generation in the fluke are very voluminous, 

 occupying with the ramifications of the alimentary tubes the 

 whole of the interior of the animal : in the diagram they are 

 not represented on the right side, in order that the distribution 

 of the intestine may be better seen ; and on the left side the ali- 

 mentary vessels are omitted, to allow the general arrangement of 

 the sexual system to be more clearly intelligible. 



These animals would seem to be completely hermaphrodite, 

 not only possessing distinct ovigerous and seminiferous canals, 

 which open separately at the surface of the body, but even 

 provided with external organs of impregnation, so that most 

 probably the co-operation of two individuals is requisite for mutual 

 fecundity. 



To commence with the female generative system, we find the 

 ovaria (h) occupying the whole circumference of the body. 

 When distended with ova, the ovigerous organ is of a yellow 

 colour ; and, when attentively examined under the microscope, is 

 seen to be made up of delicate branches of vesicles united by 

 minute filaments, so as to have a racemose appearance. From 

 these clusters of ova arise the oviferous canals, which, uniting on 

 each side of the body into two principal trunks, discharge their 

 contents into the large oviducts (g). The oviducts terminate in 

 a capacious receptacle (e), usually called the uterus ; and from 

 this a slender and convoluted tube leads to the external orifice, 

 into which a hair (d) has been inserted. On each side of the 

 uterus we find a large ramified organ, made up of csecal tubes, 

 (/,) which opens into the uterine cavity, and no doubt furnishes 

 some accessory secretion needful for the completion of the ova. 



The male apparatus occupies the centre of the body. The 

 testes (A-), in which the spermatic fluid is secreted, consist of 

 convoluted vessels of small calibre, arranged in close circular 

 folds, and so inextricably involved, that it is difficult to get a 

 clear idea of their arrangement ; but towards the middle of the 

 mesian line they become more parallel, and terminate in two 

 larger trunks (t), (one of which has been removed in the figure,) 

 which are enclosed and hidden in the seminal vessels. These 

 great canals, which run side by side in a longitudinal direction, 

 become gradually much attenuated (/), and terminate in the root 

 or capsule of the penis (m). The external male organ (n) is 



