510 



Mr. H. A. Buylis on 



about the thirtieth segment, and young mature segments 

 begin at about the sixtietli. There may be about eight or 

 nine gravid segments at the posterior end, but the number is 

 never Large. 



In a mature segment (tig. 7) there are about forty testes, 

 occupying the posterior two-thirds of the segment, and ex- 

 tending forwards on the aporal side of tiie ovary. The 

 genital pores are irregularly alternating and situated near 



Fijr. 7. 



Monopylidium stercorarium ; semi-diagrammatic drawing of a mature 

 segment (from a whole preparation). 



C.S., cirrus-sac ; K, excretor}' canal ; G.A., genital atrium ; Ov., ovary ; 

 U.S., receptaculum seminis; S., shell-gland; T., testes; V., yolk- 

 gland ; V.D., vas deferens ; Vff., vagina. 



the anterior corner of the segment. There is a muscular 

 atrium (tig. 7, G.A.) into which the male and female ducts 

 open. The cirrus-sac is small, measuring 0"15x0'037 mm. 

 The vas deferens is long and much coiled, a large mass of its 

 coils (fig. 7, V.D.) just between the cirrus-sac and the ovary 

 functioning as a seminal vesicle. The ovary consists of a 

 larger and a smaller portion, the former being on the aporal 

 side. Behindit is the yolk-gland, and between this and the 



