ANNELID GENUS CAMBARINCOLA — ^HOFFMAN 291 



a relict status, species which approximate the postulated form of the 

 ancestral stock. 



VI. Female Reproductive System 



The female sex organs are much less intricate than those of the 

 male system, and are of considerably less significance in arriving at 

 groupings of species. Perhaps of greatest utility is the general form 

 of the spermatheca in providing supplementary points of difference 

 between related forms. 



Ovaries. The ovaries of branchiobdellids are located in the coelom 

 of segment vn, and offer little for systematic use. The relative 

 amount of their development, of course, provides a measure of the 

 maturity of a specimen. In some species of the family, segment vii 

 is rather distinctly the largest of the body units, and may enlarge 

 anteriorly to somewhat overlap on the posterior part of segment vi. 

 Insofar as Camharincola is concerned, however, no appreciable 

 differences are apparent either in the ovaries or the segment in which 

 they occur. 



Spermatheca. The spermatheca, throughout the family, so far 

 as known, is a tubular structure formed by invagination of the mid- 

 ventral body wall of segment v, and of variable size and shape. It is 

 composed of several anatomically and histologically distinctive sec- 

 tions reflecting different aspects of the function of sperm reception, 

 storage, and discharge. In some genera, of which most are still 

 undescribed, the ectalmost part of the spermatheca is an enlarged, 

 muscular structure reminiscent of the bm'sa, and possibly discharging 

 a similar function. In Pterodrilus and Camharincola, at least, the 

 spermatheca begins ectally with a thin-walled, muscular duct which 

 proceeds dorsolaterad around one side of the gut, terminating in a 

 variously enlarged, fusiform to globose reservoir or ental bulb, the 

 function of which is storage of spermatozoa. Histologically this part 

 of the spermatheca differs appreciably from the duct in being only 

 slightly muscular, and in gross appearance it is frequently semi- 

 transparent or clear-walled. The diameter of this portion is subject 

 to much variation, depending largely on whether or not it happens 

 to contain sperm masses; however, the ratio of its length to that of the 

 ectal duct seems to be relatively constant, and thus is available for 

 diagnostic use. In various members of the genus, the ental bulb is 

 terminated by an abruptly smaller lobe or process, the ental process. 

 This is composed of deeply staining, small epithelial cells containing 

 much granular material. These cells are doubtless secretory in func- 

 tion. As the ental process appears in general to be present and best 

 developed in specialized members of the genus, it may be provisionally 

 considered an evolutionary improvement in the spermathecal struc- 



