BY H. LEIGHTON KESTEVEN. 281 



from the intestine by a constriction is the rectum, which extends 

 straight up to the right of and dorsal to the rest of the canal, 

 and opens in the peribranchial cavity about one-third of the way 

 up the thorax. The small anal aperture is situated at the base 

 of a four-lobed funnel-like expansion (Pl.xxvi., fig. 4). 



Reproductive organs. — The testes are placed in the postabdomen. 

 The spermatic vesicles are arranged in grape-like clusters^ and 

 from each lobe there passes a vas efferens. The vas deferens is 

 situated on the ventral side of the postabdomen; it curves across 

 to the opposite side along the distal edge of the large intestine, 

 and thence it runs parallel to the rectum to terminate nearly 

 on a level with the anus (Plate xxvi., fig. 4). The ovary is 

 situated in the peribranchial cavity, on a level with about the 

 middle of the thoracic portion of the rectum (PL xxv., firr. 9- 

 PI. xxvi., fig.4). The peculiarity of this situation caused some 

 doubts as to the correctness of the observation; the specimen fiorured 

 was, therefore, imbedded and sectioned; the evidence of the sections 

 conclusively settles all doubt. A representation of a section of the 

 ovary is shown on Plate xxvi., fig. 1. This particular ovary con- 

 tains five ova .'of large size, two of which may be described as 

 ripe, the others being somewhat smaller. The germinatino- 

 epithelium is confined to the anterior wall, and here alone are 

 ova of small size seen; the rest of the wall of the ovarj^ is lined 

 by a low cubical epithelium. The ova of largest size are invested 

 by the flattened "test-cells," some of which may be seen within 

 the peripheral portion of the ovum. The half-grown ovum is 

 apparently invested by three or four layers of low cubical cells- 

 besides this envelope of test-cells the half-grown ova are separated, 

 one from the other, by trabeculse of low epithelioid cells on a 

 thin connective tissue basis, each, however, lying free in a cavity 

 larger than itself. The stroma surrounding the youngest ova 

 invests them closely. No oviduct is to be seen, the ripe ova bein^y 

 apparently set free by the rupture of the wall of the ovary. 



It is of interest to note that the species is probably self- 

 fertilising. Ova in all stages are present in the ovary, embryos 

 in several stages of development in the peribranchial cavity 

 25 



