336 ON THE ANATOMICAL PECULIARITIES 
The alimentary canal consists, in this animal, of an oeso- 
phagus, a stomach, or membranous bag with two curvatures, 
a duodenum, or cylindrical tube with one curvature, and 
a straight cyhndrical tube answering to the intestine pro- 
per, or the ileum and colon combined. In dimensions these 
several parts were nearly as follows : 
Length. Circumference or Breadth. 
CEsophagus, . 6 inches 3^ inches 
Stomach, . 25^ 6-7 
Duodenum, . 81| 4-31-& ^ 
Intestinal tube, 24 3^-4 
The oesophagus is a cylindrical tubular organ, extend- 
ing from the posterior part of the throat downward, and 
slightly to the left, about 6 or 7 inches. In diameter it 
varies from 1| to 2 inches. When cut open by a longitu- 
dinal incision, the whole breadth of the tube is 3^ inches, 
which may be regarded as equivalent nearly to its average 
circumference. Its parietes are membranous, varying in 
thickness from 2 to 3 lines- — diminishing, however, when 
the tube is stretched. The substance of this tube consists 
of three distinct tissues. The external is a sort of tendi- 
nous fascia, with longitudinal fibres particularly distinct 
along the posterior part of the tube. Beneath this is a 
layer of muscular fibres, disposed in a circular direction 
round the tube, and constituting with the connecting cel- 
lular tissue the greater part of its substance. Within this 
again is placed the proper oesophageal membrane, a firm 
tenacious substance of pearl-white colour, quite opaque^ and 
half a line thick. 
The free surface of this latter membrane is projected into 
numerous conical and pyramidal papillcB^ which rise above 
its level to the extent of a line, or a line and a half, and a 
few tubercular eminences, not quite so prominent, but with 
