140 MR. P, CHALMERS MITCHELL ON THE (Jan. 14, 
end—extension of gut—has been attained in different groups, would 
seem to offer a field of enquiry that may ultimately give important 
results bearing on the problem of divergent evolution. Dr. Gadow 
has shown that the modes of coiling the gut have systematic 
value: so far as my material has been able to take me, it looks as 
if the divergencies were grouped indifferently around the common 
type. 
RaTit &. 
In the Cassowary (fig. 3) the common type is retained with.an 
almost diagrammatic simplicity. The duodenum is a short, very 
Fig. 3. 
Casuarius ; intestinal tract. 
wide loop, and presents the peculiarity, which may have been 
an individual abnormality in my specimen, that the hepatic and 
pancreatic ducts open on a wide diverticulum of the distal limb of 
the loop. The circular fold of mesentery has the very slightly 
folded gut suspended at its circumference, and the remains of the 
yolk-sac appear as a short cecum in the middle of the loop. The 
rectum is short and straight, and the ceca are in the typical 
position. The blood-vessels are absolutely typical. 
The Emu which I examined (Dromeus nove-hollandice) was 
identical in its main features with the Cassowary, and it is 
unnecessary to give a separate drawing. The duodenum was 
narrower and longer, and the hepatic and pancreatic ducts opened 
separately into the duodenum, not upon a common diverticulum. 
The Ostrich (fig. 4), which was the fine male known as the Queen’s 
Ostrich, presented an important deviation. The first two parts of 
the intestine and the three great veins were according to type, 
the yolk-sae diverticulum being conspicuous on the circular loop 
opposite the end of the median mesenteric vein. The distal limb 
of the duodenum presented a short lateral diverticulum, and the 
ceca are relatively longer than in Casuwarius and, as has been 
