218 FRANK E. BEDDARD. 
section through the csophagus of a worm. Its walls are 
muscular and stout. They are lined within by a layer of 
darkly staining cells which have much the appearance of a 
low columnar epithelium ; the lumen, however, is not simple. 
Numerous folds of the lining membrane are visible, which 
project far into the lumen, and nearly meet in the centre. 
These folds have a fairly regular arrangement. They are not 
only folds of the lining epithelium, but also of the strong 
muscular layer. This anterior diverticulum gradually passes 
into the bursa. The latter is a somewhat flattened sac, with 
strong muscular walls. It is lined by a regular columnar 
epithelium. This epithelium is markedly different in appear- 
ance from the epithelium lining the diverticulum of the sper- 
matothecal sac; the two layers do not in any way pass into 
each other. In a-series of sections the epithelium of the pouch 
terminates more or less abruptly; near to its end it gets to 
be covered by the cells of the diverticulum, which ultimately 
replace it. In a series of sections quite complete through the 
anterior of the two genital pores it was impossible to find any 
external aperture. This was also the case with a second 
series. Both worms, it should be said, were sexually mature. 
The epithelial lining of the pouch already referred to dips 
down towards the epidermis. Some little way above the 
epidermis it ends abruptly, and the lining of the sac is made 
up of cells of a quite different appearance. There is, however, 
no communication that I could discover between the inside of 
the bursa and the exterior of the body. A moderately thick 
layer, chiefly cellular, blocks the spot where the aperture 
should be. The principal part of the spermatothecal pouch 
lies behind the aperture. At first the pouch is lined with 
epidermic cells entirely similar to those which line the bursa. 
These cells form numerous folds in the interior of the sac. 
The folds, however, are not, as in the anterior diverticulum, 
supported by upgrowths of the muscular layer. Further back 
still the folds die away. At first, as already said, the pouch 
is lined by cells which resemble those of the bursa, and must 
be, I should imagine, formed by an ingrowth of the epidermis. 
