CURTIS: LIFE HISTORY OF PLANARIA MACULATA. 545 
{va) extends dorsally and posteriorly. This short canal, which I 
•designate as vagina, reaches almost to the basal membrane on the 
dorsal side, before it splits into the stalk of the nterns running ante¬ 
riorly and the common oviduct running posteriorly on the midline 
(pi. 12, figs. 33, 34). The atrial cavity extends i30steriorly a short 
distance beneath the vagina and is here thrown into one or two large 
folds which run lengthwise. These folds are glandular and are per¬ 
haps homologous with the “ muscnlo-drusen ” organs mentioned bj^ 
Ijirna (’84) in his description of Pohjcelis tenuis^ though they are 
not constant in shape or occurrence and the cavity of the atrium is 
no further complicated than by the division into an anterior portion 
containing the penis and a posterior which receives the female 
elements. Besides the secretions of the unicellular glands which 
surround the atrium and enter the vagina, the epithelial lining of 
the atrium seems to be actively at work producing a secretion which 
appears as spherical masses detaching themselves from the cells and 
covering the surface several layers deep. 
The stalk of the uterus, as above mentioned, extends forward from 
the vagina along the midline as a small tube Avhich in many sections 
shows indications of contraction, for the outline of its lumen is folded. 
In front of the penis it expands into a spherical uterus such as is 
found in many planarians (pi. 12, figs. 33, 34, u). During the egg 
laying season, this cavity when seen in transverse section is as large 
as the pharyngeal pocket and extends right uj) to the dorsal and 
ventral basal membranes. Within the uterus I’ have found what 
were unquestionably masses of spermatozoa since they had the same 
appearance as the spermatozoa found in the seminal vesicles. In 
some instances I also found what appeared to be the egg capsules 
in process of formation. Almost every live specimen when seen 
from the ventral side shows a reddish brown mass in the position 
of the uterus, as though the uterus contained one of the brown egg 
capsules. This color must, however, be due to the color of the 
uterus itself, for it shows exactly the same when there is no trace of 
a capsule. 
The ovaries (pi. 19, fig. 56, o) lie about one fourth the entire 
length of the animal from its anterior end and are in the usual ven- 
O 
tral position just inside the nerve cord. They are of considerable 
.size, often more in diameter than one half the dorso-ventral thick¬ 
ness of the specimen. Figure 52 (plate 17) represents a transverse 
