1889.] CONVOLUTIONS IN BIRDS. 311 
back, and especially the terminal end of the second resembles some- 
what a plagioccelous formation. The Pteroclidee have consequently 
various points in common with several rather diverse groups; they agree 
with the Rallidee in having the 2nd and 3rd loops left-handed, but 
differ from them and from the Limicolz in having all the loops closed. 
They differ from the Rallidze and agree with the Columbe and lower 
Limicolz in the number of loops. All this tends to indicate that 
the Pteroclidee have branched off from the common Gralline stock 
before the separation of the latter into Limicole and Rallide had 
taken effect, and before either typical Columbz or Gallinze were 
developed. That they have, in the diagram, to be placed in the 
isoceelous circle—which really belongs to totally different birds— 
shows also that they have made an early and special departure. 
The Alcide are periccelous and strictly orthoccelous ; they agree 
with the Laro-Limicolz in the configuration of their first three loops, 
but they differ from them in the number of loops, which is at least 
six, the last three of which are left-handed. The Alcide seem to have 
started from some low Limicoline forms and to have branched off 
early into astrictly orthoccelous direction. ‘They are, in this respect, 
further removed from the Laride (least so from the Terns), and 
render the term Gavi somewhat vague. They approach the Pygo- 
podes (Colymbidz and Podicipitide). 
The Colymbidz show unmistakable affinities with what may be 
called generalized or low Gralline forms; their five loops are closed, 
orthoccelous, and alternating. The Podicipitide differ somewhat 
from the Colymbidee, and besides possessing some special pecu- 
liarities, approach the Gralle more closely than do the Colymbide ; 
at the same time in the possession of a pyloric dilatation they have a 
feature in common with certain Fulicariz and with the Steganopodes 
and Herodii. A peculiar resemblance also exists between Podiceps 
and Podica in the widely open and irregularly shaped last intestinal 
loop. All this assigns a lower position to the Podicipitidee than to 
the Colymbidze, and gives them unequal rank, although the validity 
of the name Pygopodes can be maintained. They connect the large 
Gralline group with the following congregation, of which the Herodii, 
Steganopodes, Tubinares, and Spheniscide are all divergent types. 
A very close connection exists between the Herodii and the Stegano- 
podes, and this is supported by numerous other characters. The 
Tubinares are in more than one respect the most specialized outcome 
of this great collective order, and reach in the typically mesogyrous 
Procellariine their highest development; whilst Puffinus and 
Dicmedea are more generalized, and Ossifraga takes up a somewhat 
intermediate position. There are, in this respect, striking resem- 
blances, of uncertain value however, with the Laro-Limicole ; and 
thus we arrive at the same conclusion as Fuerbringer, who assigns to 
the Tubinares a position somewhat intermediate between but rather 
distant from the Laro-Limicolee and Steganopodes. 
The Spheniscide are now a very specialized group. They possess 
undeniable characters in common with the Pygopodes, Stegano- 
podes, and Tubinares; they are on the whole orthoccelous, but the 
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