64 
portion of the post-pyloric intestine which bears the 
pyloric ceca and receives the bile and pancreatic ducts. 
There is no essential difference between intestine and 
rectum, but it is convenient to distinguish the terminal 
portion of the alimentary canal from that immediately 
preceding it. 
The appearance presented by the viscera cn opening 
the body cavity of a large plaice from the ocular side 
varies considerably with the condition of the reproductive 
organs and with the sex- Fig. 20, pl. V., represents the 
‘ 
relations of the viscera in a “‘ripe’’ and mature female. 
The great increase in volume of the ovaries has crowded 
the greater portion of the intestine towards the dorsal 
part of the body cavity; the duodenum is pressed for- 
ward; the rectum being more fixed than the rest cf the 
post-pyloric intestine is not much displaced: the stomach 
occupies nearly its normal position. Fig. 21 shows the 
condition of the viscera in a mature female which has just 
spawned. The greater portion of the intestine has been 
removed, however, in order to display the deeper viscera. 
It would form two S-shaped loops overlying and hiding 
most of the structures indicated in the figure. 
The @sophagus is very short, and almost immediately 
on entering the body cavity expands into the stomach. 
Its walls are very thick and are composed almost entirely 
of a transversely disposed layer of striated muscle fibres. 
The external longitudinal muscle layer is thin, and 
appears to consist of unstriated fibres. The mucosa con- 
sists of a layer of columnar cells crowded with “ goblet ”’ 
cells. As observed in the dead fish, the lumen of the 
esophagus is greatly reduced, though it is evident from 
the nature of the food that it is capable of considerable 
expansion. 
The layer known as the muscularis mucosxe does not 
