2J2 JOHANNA M. DIECKMANN. 



philus; in this form the tubules are at first solid outgrowths, 

 the lumen developing first in the expanded distal portion, and 

 later in its slender neck. 



The common tube of the spermatheca in Enrycea is regarded 

 by Koehring (see above) as a portion of the cloacal wall. This 

 coincides with the findings in Gyrinophilus. It is possible that 

 the "thick walls of the invagination " (Koehring) correspond 

 to the "cellular area" described in the "first unmistakable 

 spermatheca" in this study of Gyrinophilus. In this specimen 

 the mass of epithelial cells from which the tubules spring, and 

 into which a portion of the cloacal lumen has been drawn, is 

 very thick. It is also difficult to distinguish the basement 

 membrane which sets off the highly cellular tissue outside from 

 the equally highly nucleated epithelium. Together they might 

 be gaid to constitute a "thick wall" for the cloacal depression 

 or common tube. 



There are several features in the development of the cloaca 

 and spermatheca which must be accounted for. I shall consider 

 first the change in direction of the tubules to one which is chiefly 

 caudad. Coincident with this change, the entire spermatheca 

 shifts from a position dorsal to the vent, to one ahead of the 

 cephalic end of the vent, while ventral glands come to lie caudal 

 to the level of the spermatheca. Moreover, the cloaca is rela- 

 tively and actually taller in the animal of 8.8 cm. (Figs. 14 and 

 15) than at 10.5 cm. (Figs. 16 and 17). All these facts point 

 toward an elongation and flattening of the cloaca, coincident 

 with increase in length of the whole animal. In Fig. 27 the 

 outline of an adult cloaca, relatively reduced in size, has been 

 superimposed upon the outline of a young cloaca. The long 

 arrows, a and b, indicate the shifting of parts which would 

 flatten the cloaca, bring ventral glands caudal to the level of 

 the spermatheca, and bring the spermatheca cephalic to the 

 vent. During the change of position of the spermatheca, its 

 tubules are turned caudad. 



Elongation of the cloaca, however, does not explain the 

 development of the dorsal elevation, the fusion of its two limbs 

 cephalic to the spermatheca, nor the development of the diver- 

 ticulum. These are interpreted as being due to an overgrowth 



