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PROCEEDmGS OF THE NATIONAL MUSEUM 



fashion (fig. 84,a). They fill practically all the space between the 

 cavity of the antrum and the dorsal and ventral body walls. Most of 

 the fibers of the muscle masses course around the antrum in a circular 

 direction. The antrum presents numerous bulges into the lumen 

 but its exact shape could not be determined because of the many 

 cracks. It opens below by what appeared to be a very large gonopore 

 but the limits of this also remain uncertain. An anterior ventral 

 diverticulum of the antrum is provided with eosinophilous glands, 

 at least along its lower wall, and probably represents a prostate. It 



b 



Figure 83. — a, Indistylochus hewatti, sagittal view of copulatory apparatuses; h, Anaiidro- 

 plana muscularis, dorsal view. (For explanation see page 116.) 



