712 PROCEEDINGS OF THE ACADEMY OF [DeC, 



In the breeding season, when the gonads are swollen and en- 

 larged, the intestinal ctcca are under such- pressure that their 

 opposite walls are frequently in contact. Wilson (1900) believes 

 that the lateral ca^ca do not function under these conditions, and 

 quotes the statement of M'Intosh (1873), that " the glandular 

 elements in the wall of the digestive tract undergo a certain 

 amount of atrophy during the period of reproductive perfection." 

 Wilson adds, in respect to (Jerebratulus ladeus, p. 115: " For a 

 long time, therefore, these intestinal pouches can function very 

 little, if at all, and so they contribute nothing to the nourishment 

 of the body." I should be unwilling to state that the lateral 

 pouches in Zygeupolia take no part in the absorption of food, for 

 I have found some cells of the lateral cseca that evidently con- 

 tained food vacuoles, in spite of the fact that the ctecum was 

 greatly pressed by the adjoining gonads; but the cells of the creca 

 are certainly under great disadvantages at this period. 

 • Toward the posterior end of the body (see fig. 17), the lateral 

 cseca decrease more and more in size, until finally the intestine is 

 once more a simple tube, Plate XLI, fig. 26, E.I. This portion 

 of the alimentary tract is variously termed the "anal portion of 

 the intestine," the " end intestine" ("Enddarm," Burger) and 

 the "rectum" (Coe, 1895 a). 



The end intestine, as it will here be termed, in Zygeupolia is 

 about .8 mm. long. The cells are the same absorptive cells that 

 are found in the middle intestine, with an occasional gland cell, so 

 that histologically the end intestine is the same as the middle intes- 

 tine, and may be regarded as merely the terminal portion of that 

 region. 



At the junction of the caudicle and body, fig. 27, the intestine 

 curves dorsally and opens, by the anus, to the exterior on the dor- 

 sal surface of the body. The anal opening, fig. 17,^1., is small, 

 and the edges are clothed with cilia. 



10. The Reproductive System. — Zijgeupolia is dioecious. 

 The gonads, figs. 1, 24, 25, are found between the pouches of 

 the middle intestine, metamerically arranged, throughout its 

 length, the first pair of gonads occurring between the first and 

 second pairs of intestinal CiTca, and so on regularly, the gonad of 

 one side lying between two consecutive intestinal ca^ca, and oppo- 

 site to its fellow of the other side. Near the end of the middle 



