236 On the Digestive System of Birds. 
types of intestinal arrangement. These he calls Orthocela, 
Plagiocela (or Plagiobrochi), and Cyclocela. 
In the first group (Orthocela), in which he includes the 
Pygopodes, Steganopodes, Anseres, Tubinares, Erodi, Alec- 
torides, and Rallide, the chief folds, which are from five to 
eight in number, are straight and parallel to one another and 
to the long axis of the body. 
In the Plagiocela, which includes only the Rasores, the two 
middle of the four chief folds form more or less horseshoe- 
shaped loops at their extremities, and the general direction of 
the intestines always forms, more or less, an angle with the 
long axis of the body. 
In the Cyclocela one or more of the chief folds are spirally 
coiled round their ends. This division includes some of the 
Gralle, the Pelargi, Laride, Psittaci, Raptores, Columbe, 
the Coccygomorphe and Pici in part, the Cypselomorphe, and 
the Passeres. 
It is further subdivided into the Telogyri,.in which only 
the terminal part of the fold is coiled, and the Hologyri, in 
which the whole fold is so disposed, these latter, again, 
being further divided into Progyri, Mesogyri, Amphigyri, 
and Polygyri. 
But, judging from the forms associated together under 
some of these heads, the groups so named are eminently arti- 
ficial. Thus, the Raptores are divided amongst the first three, 
and under the Mesogyri are included forms as various as 
Astur, Melierax, Halcyon, and Phenicopterus. 
The paper concludes with the inevitable phytogenetic table, 
showing Dr. Gadow’s ideas of the lines of descent amongst 
birds. He holds that all the highest forms of each subdivi- 
sion belong to the Hologyri or Mesogyri, the more primitive 
ones being Orthoceela or Plagiocela. 
The figures in the plates are chiefly devoted to showing, 
in a more or less diagrammatic way, the various types of intes- 
tinal convolution described in the text, and will be found very 
useful in elucidating Dr. Gadow’s views. 
In conclusion, it seems to me that, as it is a well-known 
fact that individuals of the same species vary, sometimes very 
