HISTOLOGY OF THE LAND-PLAN AEIANS OF CEYLON. 
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a. Vesicular epithelium clothing the base of the penis. 
c. m. Circular muscles of the sheath of the penis. 
e. Its irregular epithelial lining. 
Fig. 2. Longitudinal section in the plane of the body, through the muscular bulb at the 
base of the penis. Drawn with the camera. 
The rounded muscular mass here seen is that from which the penis takes 
its origin, and the fibres seen passing into the penis in fig. 1, Plate XIII., are 
portions of this muscular bulb. The fibres of the bulb are continuous externally 
with those of the sheath of the penis, internally with those of the penis itself. 
The oval fissure in the middle, which stands out in relief as very slightly tinged 
with carmine, is the prostate cavity nearly filled with glandular substance. 
The retractor muscles ( u ) are seen passing inwards, and appear to join the 
septa between the glandular crypts of the prostate, as in fig. 3. 
c. Cavity of sheath of penis. 
e. Epithelium of the sheath. 
em. Its circular muscular coat. 
m. Muscular mass of bulb of penis. 
u. Retractor muscles. 
I. C. Internal circular muscular coat. 
Po. Glandular substance of prostate. 
Fig. 3. Small portion of the innermost region of a transverse section of the base of the 
penis of Bipalium Diana , magnified. Drawn with the camera. 
The retractor muscles (W, W) are seen passing inwards between the 
bundles of longitudinal muscular fibres (L.P., L.P., L.P.), traversing the dense 
internal circular muscular ring (I. C.), and forming a network in the space which 
intervenes between the internal circular muscles and the glandular prostatic 
tissue (Pr.). The actual termination of the retractor muscles was not deter- 
mined, hut they often have the appearance of becoming continuous with the 
glandular bodies (Pr.). 
I. C. Internal muscular layer of penis. 
Pr. Glandular prostatic tissue. 
L. P. Longitudinal muscles of the penis. 
W, W. Branched retractor muscles. 
C. M. Scattered circular muscular fibres. 
Fig. 4. Testis of Bipalium Diana in a plane parallel to the inferior surface of the 
body. A section of the organ is seen to be circular in outline. The organ is 
enclosed in a capsule consisting of an outer layer of loose tissue with large 
open spaces in it, and an inner layer of compact tissue. There is an opening 
in the capsule laterally, where the interior cavity of the gland becomes con 
tinuous with that of its ducts, and its epithelium is thickened opposite the 
point of entrance into it of the duct from each testis. The duct is narrower 
t 2 
