The Anatomy of OpistJiopatus cinctipes. 89 



individual legs in' other parts of the body, are not always present. 

 This would indicate that these organs are all similar to one another, 

 and physiologically of minor importance, like the crural glands in the 

 females of Peripatopsis, in which they may be absent or present in 

 corresponding legs of different individuals of the same species. In 

 ^ny case the accessory glands of the genital segment in Peripatoides 

 very closely resemble those of Opisthopatus in the position of their 

 external openings, hence the importance of knowing how far they 

 resemble the crural glands of the other legs in the former genus. 



Peripatopsis. — In this genus only a single pair of accessory glands 

 -occurs, the openings of which are situated in the genital segment. 

 'The glands of P. capensis were first drawn by Balfour and described 

 by Moseley and Sedgwick (in Balfour, 1883, p. 36, fig. 43), and 

 subsequently by Miss Sheldon (1889). I have myself examined 

 them in P. capensis and halfouri. 



They form a pair of short blind tubes, the walls of which are 

 •composed of a high epithelium covered by a very thin layer of flat- 

 nucleated cells, evidently muscular in function. Altogether they 

 closely resemble the enlarged crural glands, when seen in cross- 

 section. They pass over gradually into the ducts, which are very 

 fine — much slenderer, in fact, than the ductus ejaculatorius, the walls 

 •of which they pierce, as correctly stated by Willey (1898, p. 17). 

 Each duct discharges separately into the lateral wings of the ductus 

 ejaculatorius near the posterior extremity of the latter, the lumen of 

 which exhibits here a cruciform transverse section (see below, p. 93). 

 Peripatus. — In this genus, according to Gaffron (1885) and Kennel 

 {1886, p. 71), the accessory glands (or " anal glands," as they are 

 usually called) of the male form a pair of pear-shaped vesicles with 

 "two ducts, which discharge each into a chamber, opening separately 

 -on each side of the anus. No accessory glands have, as yet, been 

 found in the genital segment itself. 



Paraperipatus. — In the male of this curious form, according to 

 the recent investigations of A. Willey, a pair of accessory glands 

 {"pygidial glands") occur, which discharge into a common muscular 

 bulbus situated immediately above the rectum, and itself opening 

 -externally on the dorsal surface just in front of the anus. In this 

 form the genital segment has lost its pair of limbs, and it is not quite 

 •clear whether the accessory glands are postgenital or not. 



Phylocjeny of the accessory glands in Onychophora. — [a) The 

 accessory glands of the genital segment are plainly morphologically 

 equivalent to, and serially homologous with, the crural glands, since 

 the nephridia of this segment have been shown by Kennel and 



