144 MR. P, CHALMERS MITCHELL ON THE [Jan. 14, 
gated, the greater part of the elongation having occurred in the 
circular loop. The ceca are small, and lie on the third part of 
the gut, some distance below where it joins the circular loop. 
As usually happens when the ceca are reduced, the last part of 
the circular loop is pulled out into a long free loop, which, in the 
natural position, is closely attached to the under surface of the 
duodenum, and gives a vein to the duodenal vein. Platalea leuco- 
Platalea leucorodia ; intestinal tract. 2, short-circuiting vessel cut across. 
rodia, the Spoonbill (fig. 8), shows the least differentiation among 
those that I have examined. The duodenum is very long and is 
curved far round to the left in the abdominal cavity. The circular 
loop is enormously expanded, and forms a rough spiral, of which 
the middle mesenteric vein, running out to the vestige of the yolk- 
duct, forms the axis. The figure represents this after it has been 
dissected out and is more diagrammatic than most of the drawings 
I give. The most important points to which I would call attention 
are: that the yolk vestige, though at the end of the spiral, is much 
nearer the posterior than the anterior end of the circular loop, 
owing to the greater development of the first half of the circular 
loop; and the fact that on the whole the minor loops of the 
circular loop are of similar length, with the exception of the last 
loop. It is in this respect especially that the Spoonbill has departed 
less than other Ciconiiformes from the type. The veins of the gut 
are almost diagrammatic in the simplicity of their arrangement, 
the only peculiarity being the short-circuiting branch from the 
duodenal vein to the distal loop of the circular loop. 
In Pseudotantalus ibis the duodenum, which was curved in 
Platalea, is very much elongated and twisted into a spiral. The 
first portion of the circular loop is elongated into a separate 
loop: the remainder of the circular loop is more primitive 
even than in Platalea, consisting of a number of nearly equal 
radial folds at the circumference of the whole fold. There is a very 
