594 



ZOOLOGY 



SECT. 



the extremities of the oral papillae, may be modified coxal glands : 

 the secretion of these is discharged in the form of a number of 

 fine viscid threads when the animal is irritated, and appears to 

 serve a defensive purpose. 



The nervous system consists of a brain (brn.) situated in the 

 head, and of two longitudinal nerve cords (ne. co.) which run parallel 

 with one another throughout the body to the posterior end, where 

 they join together behind the anal aperture. A number of very 

 fine transverse commissures, more numerous than the segments 

 (i.e., than the pairs of limbs), connect the two cords together to 

 form a ladder-like nervous system comparable to that of some 

 of the Flat Worms. The cords are very slightly swollen opposite 

 each pair of limbs : nerve-cells cover them uniformly throughout 

 their entire length. The brain gives off nerves to the antennae. 



The nerves to the jaws are 

 given off just where the 

 brain passes into the longi- 

 tudinal nerve cords. 



The excretory organs are 

 nephridia (Fig. 490) of the 

 type of those of the Annu- 

 lata, situated in pairs in the 

 lateral compartments of the 

 body-cavity, and opening on 

 the lower surfaces of the legs 

 bases. Each nepliri- 



J 



.c. i, s.c. 2, s.c. 3, s.c. 4, successive regions of closed internal vesicle, repre- 



coiled portion ; s.o.t., third portion of nephridium r *. 



broken off at p.f from the internal vesicle, which Senting a Section OI * tne 



BaK^P' ^* *<*"*'* ***-*" co3lome, into which by a 



funnel-shaped aperture leads 



a looped tube (s.c.). and a dilated terminal vesicle (s.), situated close to 

 the external opening. The salivary glands are, as shown by the study 

 of their development, specially modified nephridia, as apparently 

 also are a pair of glands the anal glands opening close to the anus. 



Reproductive organs. Peripatus has the sexes distinct. In 

 the female there are two tubular ovaries, a pair of oviducts, and 

 two uteri, the latter in the form of long curved tubes which unite 

 behind in a median vagina opening on the exterior on the ventral 

 surface, between the legs of the last pair or behind them. In the 

 oviparous forms the opening is situated at the end of a long cylin- 

 drical process the ovipositor. In some species, connected with 

 each uterus where it leaves the ovary, are two diverticula the 

 receptaculum seminis and receptaculum ovorum. In certain species 

 one or other of these may be absent. 



In the male there are two tubular testes, each with a narrow vas 

 efferens opening by a funnel-like aperture into a vesicula seminalis ; 



