244 PSEUDO-HELMINTHS. 



rounded off, turns sharply on itself to form a clift and an open- 

 ing, in which are placed the organs of generation. 



The nervous system is quite of an elementary nature. So far 

 as I can discover, it consists of a single cephalic ganglion, which 

 sends off one or more minute branches to the proboscis or oral 

 opening. Organs of special sense are entirely wanting. There is 

 nothing remarkable about the mouth. It is formed for suctorial 

 purposes only. In form and structure it is perfectly circular, and 

 is divided into two or three rings, which are acted upon by 

 separate sets of circular and radial muscular fibres. The inner or 

 middle ring, when opened out, divides into six etjual parts, which 

 turn outwards upon the inner lip, somewhat like the petals of 

 certain flowers. The muscular layer is capable, when set in 

 action, of producing a considerable vacuum, while the radial set 

 will convert the innermost disc into a sphincter, closing up the 

 oesophageal opening. The oral arrangement of the male appears 

 to me to differ slightly. I make out a third inner divided disc, 

 with a series of equally disposed chitinous teeth. 



Dr. Cobbold, in his valuable work on " Entozoa," in a wood- 

 cut drawing of the female, represents the disc I allude to, but this 

 is an error on his part, for this is only seen in the male. The 

 vulva and uterus of the female is located unusually high up in the 

 body, and here the male is securely attached. In this case it is 

 the female who shows herself an imperious monogamist, for 

 having selected a mate she compels him to cling to her body, and 

 thus carries him about with her for the rest of her natural life. It 

 has long been in dispute whether or not actual incorporation of 

 substances takes place between the sexes. Von Seibold taught 

 that there is actual incorporation, but I believe this is quite a 

 mistaken view, founded, of course, on the very intimate nature of 

 the connection, although the same kind of joining of the sexes is 

 seen to take place in certain of the Lepidoptera — the silkworm 

 moth, for instance. 



The male organ of generation is of a very distinctive cha- 

 racter. It consists of a double set of trifurcate, finger-like series 

 of processes, and an intermediate tripartite penis. These several 

 parts, on passing through the vulva, have an antagonistic action to 

 the other. I have been unable to satisfy myself of the existence 



