284 PERIPATUS, MYRIOPODS, AND INSECTS. 



and a wide vesicle which opens near the base of each leg, the two last 

 parts being invaginations of the ectoderm. This is the only certain case 

 of their occurrence in a Tracheate. The salivary glands and the genital 

 ducts aie probably modified nephridia. It may be noted, too, that the 

 same is perhaps true of the "coxal glands" of Limulus and of the 

 antennary glands of Crustaceans. 



Crural Glands lie in the legs and open to the exterior. Their 

 meaning is uncertain, their occurrence is variable. Thus in P. 

 edwardsii they occur in the males only, in P. capensis they are present 

 in both sexes. In the male of P. capensis the last pair are very long 

 (Fig. 121, a.g. ). The large mucus glands, which pour forth slime from 

 the oral papillte, are regarded as modified crural glands. 



Fig. 



-Dissection of Peripalus capensis. — 

 After Balfour. 



at., Antennae; or.p., oral papillae; eg., cerebral ganglia; sl.d., 

 duct of slime gland {sLg.y, s.o.8, eighth segmental organ or 

 nephridium ; v.c., ventral nerve connected by transverse com- 

 missures (co.) with its fellow; s.0.17, seventeenth nephridium; 

 g.o., genital aperture ; A., anus ; p.d.c, posterior commissure ; 

 F.lf, seventeenth appendage; a.g., last crural gland, that of 

 the opposite side is marked v.g. ; F.i, F.2, first and second 

 legs; oe.co., oesophageal nerve commissure; oe., cesophagus ; 

 ph., pharynx, the remainder of the gut is removed. 



Reproductive system. — [a) Female (of P. edwardsii). — From the 

 two ovaries, which are surrounded by one connective tissue sheath, and 

 arise, as usual, from the ccelomic epithelium, the ova pass by two long 

 ducts leading to a common terminal vagina opening between the second 

 last legs. These ducts are for the most part uteri, but on what may be 

 called the oviduct portions adjoining the ovaries, there are two pairs of 

 pouches — (a) a pair of receptacula seminis (for storing the spermatozoa 

 received during copulation), and a pair of receptacula ovorum for storing 

 fertilised eggs. 



The eggs are hatched in the uteri, and all stages are there to be found 

 in regular order. The young embryos seem to be connected to the wall 

 of the uterus by what has been called a " placenta," so suggestive is it 

 of mammalian gestation. The older embryos lose this " placenta," but 



