INTESTINAL TRACT OF PENGUINS. 21 
nately my material has been restricted to nestlings only. Nevertheless it seems to me 
that the peculiarities in the tracts in question are too marked to be materially affected 
by age. Dr. Chalmers Mitchell has shown that Catarrhactes, Spheniscus and Apteno- 
dytes agree rather closely one with another in the great length of Meckel’s tract, and 
in the form of the supra-duodenal loop, which is simple and in all of considerable 
length—relatively longest in Spheniscus and shortest in Eudyptes. Spheniscus and 
Catarrhactes alike have the duodenal loop of great length and thrown into a series of 
minor loops, wherein they differ from Aptenodytes, in which the duodenal loop is simple, 
of great length, and coiled upon itself. 
It would now appear, from what follows, that while among the penguins there is 
to be found a common general 
resemblance in the convolu- 
tions of this tract, there is, at 
the same time, a greater range 
of differences between the 
species of a genus than might 
have been supposed; how 
great this range may be is a 
matter for further research. 
Thus, while in the King Pen- 
guin, A. patagonica, the duo- 
denal loop is a simple closed 
loop coiled upon itself; in 
the Emperor, A. forsteri, it 
forms what may best be 
described perhaps as a series 
of interlocking U-shaped loops 
(fi g. 6) : while in the Adélie FIG. 7,—THE mais | ec Ore ernie ia Pygoscelis adeliz. 
Penguin, Pygoscelis adelie, 
the loop is, as in the King Penguin, simple and coiled, but the coils, however, are 
much more voluminous, as may be seen in fig. 7. The Adélie and Emperor Penguins 
show a further common resemblance in that in both species the supraduodenal loop is 
folded back upon itself instead of forming a single loop as in the other genera already 
described : while the tract in Pygoscelis is still further remarkable in that the loops in 
Meckel’s tract appear to be fewer in number than in any other penguin yet ex- 
amined, though it must be remembered that the condition here described is that of a 
nestling. The number of loops may increase with age. 
Meckel’s diverticulum in the young Emperor Penguin is situated, not as usual at 
or near the end of the apex of a loop, but at the bottom of the valley between two 
adjacent loops (fig. 8). 
The very remarkable difference displayed by the intestinal tracts of the King and 
