470 STANLEY C. BALL 



closely together one behind another, as Patterson suggests, like 

 a "rouleau of coins." The ovary increases greatly in diameter 

 toward its posterior end. At about the mid-length of the ani- 

 mal it turns inward to meet the oviduct (figs. 3, 4; text fig. 2). 



The enormous paired vitellaria discharge their contents into 

 the same ducts as the ovaries. Each vitellarium sends branches 

 anteriorly and posteriorly. At the height of their development 

 the numerous anastomosed branches completely surround the 

 intestine, occupying practically the whole region between it 

 and the body wall (fig. 3). The anterior lobes lie above the 

 ovaries and intestine; in extreme cases a few branches grow 

 forward to a point above the brain. Single rows of yolk cells 

 constitute the ultimate lobes. Indeed, individual cells fre- 

 quently lie isolated in the parenchyma. 



So closely do the vitellaria press upon the ovaries at the 

 posterior ends of the latter and for some distance along their 

 dorsal surfaces that the two organs occasionally appear to be 

 joined into a single germo-vitellarium on each side of the body. 

 As a matter of fact, however, if they join at all it is only at the 

 point where they meet the oviduct — or better, the 'vitello- 

 oviduct.' The stalks of the two vitellaria, as seen in figure 4, 

 are separated only by a thin partition of mesenchyme. No 

 cellular wall has been observed between the ends of the oviducts 

 and the vitellaria. As shown in this figure, yolk cells often 

 appear in the upper end of the antrum, indicating that they 

 are likely to be liberated by any slight pressure in this region. 



Posterior to the seminal vesicle a dorsal diverticulum of the 

 atrium commune is considered by Patterson to be the degen- 

 erate seminal receptacle, although he found no spermatozoa 

 in the sac. In several of our preparations it contains a mass 

 of spermatozoa (fig. 9) which so distend it that the top is on 

 a level with that of the seminal vesicle. This organ is rather 

 to be regarded as a bursa copulatrix than as a receptaculum 

 seminis; the spermatozoa, during copulation, are first received 

 in this dorsal pouch of the atrium commune and afterwards pass 

 into the antrum femininum. The atrium is lined internally 

 with a high columnar epithelium, externally by a single layer 



