The Anatomy of Opisthopatics cinctipes. 77 



clothed throughout its length with a very thick muscular layer, 

 which is indeed much thicker than the internal epithelium and 

 evidently acts as a strong constrictor. The duct itself is compressed, 

 its lumen being slit-like in cross-section, and it opens, as already 

 stated by Moseley and Sedgwick (in Balfour, 1883), by means of a 

 slit-like opening at the apex of a large whitish papilla, situated on 

 the ventral surface. This papilla is relatively larger than the corre- 

 sponding papillae of the crural glands in Opisthopatus, and differs 

 also in being non-retractile and not enclosed in a ring-like fold of 

 epidermis. It is always conspicuous, and forms a well-known 

 character for distinguishing the male. 



A constrictor muscle, similar to that of the enlarged glands, only 

 very much thinner and not more than two cell layers deep, clothes 

 the ducts of the smaller crural glands, which also discharge at the 

 apex of a distinct but smaller papilla, situated between the first 

 and third rows of papillae on the ventral surface of the legs (counting 

 from the proximal pad) but not necessarily in the second row. 

 This papilla may often be easily distinguished in spirit specimens, 

 especially when the adjacent papillse are pigmented, owing to its 

 paler colour, or when a piece of coagulated secretion projects from 

 the orifice at its apex. Sometimes the external opening is situated 

 eccentrically at the edge of the broad apex of the papilla, but I have 

 never observed it placed between the papillae in either sex in any 

 species (except perhaps in the case of P. clavigera).-'- 



Both Balfour and Miss Sheldon state that crural glands are 

 present in P. capensis in all the legs with the exception of the first 

 pair, while the former author implies, and the latter distinctly states, 

 that they occur in both sexes. According to Willey (p. 7), however, 

 no crural glands were present in those legs of the female examined 

 by him, and he suggests that perhaps the fat body in the legs has 

 been confused with the glands. In order to ascertain whether crural 

 glands were present or not, I made sections of legs, mostly chosen 

 at random, from all the species of Peripatopsis with the following 

 results : — 



In a half-grown $ capensis (19 mm. long in contracted condition), 

 sectioned from end to end, crural glands were quite absent from the 

 first 5 pairs, but present and well developed in the 6th to 17th pairs 

 inclusive. They resembled the corresponding glands of the male, 

 excepting in the case of the 17th pair of legs, the glands of which 



* The statement made by Willey (1898, p. 7), that only the openings of the 

 enlarged pair of glands in the male of P. capensis are horn on white papillae is 

 incorrect. 



