64 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 



151), SO that each ovary contains but a single ovum, and this is 

 often separated from the next by several intestinal lobes. In 

 Emplectonema hdrgeri as many as 20 to 30 sperraaries are some- 

 times met with in a single section. The anterior ones are situated 

 dorsally and open on the dorsal aspect of the body, while those 

 found in the intestinal region lie on all sides of the alimentary canal 

 and open to the exterior on the ventral as well as on the dorsal side 

 of the body. This is equally ti'ue of Paraneniertes peregrina and 

 P. carnea. 



In Carinella and Caeinomella the sexual glands when fully 

 mature are packed closely together throughout the whole intestinal 

 region, and a transverse section of the body may cut several such 

 sacs on each side. Each sac has its own efferent duct, which passes 

 through the body walls to open to the exterior on the dorso-lateral 

 aspect of the body. The sexual glands occupy the dorsal half of 

 the body, and as some lie much nearer the lateral margin than 

 others it happens that their ducts, instead of being placed in a 

 single row, are scattered over a broad area situated between the 

 median line and the lateral margin. The genital pores of many 

 nemerteans can be seen in life as minute white dots along the 

 dorso-lateral aspects of the body. They are quite conspicuous in 

 Micrura verrilli (PI. 3, fig. 35). 



In most species of Carinella the sexual glands are not to be 

 found except at the time when the sexual products are developing, 

 and after these products are discharged all trace of the gland itself 

 disa2)pears. In C. frenata, however, the ovaries which are to 

 develop the following year are established before the eggs of one 

 season are fully mature, as is the case in most of the Hoplo- and 

 Heteronemertea. 



In process of formation certain cells situated in the parenchyma 

 internal to the lateral nerves multiply and collect in small groups. 

 Each such group grows rapidly in size and in the number of cells 

 composing it. Then certain of these cells ari-ange themselves next 

 the parenchyma to form a thin membrane enclosing the other cells 

 as in a cavity. Thus a sexual sac is formed, and the cells M'ithin 

 the sac eventually become metamorphosed into the mature sexual 

 elements. When nearly mature the wall of the sac grows outward 

 into the muscular layers of the body wall as a simple tube lined with 

 flattened epithelium (PI. 10, fig. 63; PI. 20, figs. 122, 125-127). 



