1896.] . OBLIQUE SEPTA IN THE PASSERINES. 229 
as I have examined—both Acromyodian and Mesomyodian it should 
be observed—to the peculiarity which they show in the arrange- 
ment of the oblique septa. Another distinctive feature of Passerine 
anatomy is quite desirable. So far as we know at present, there 
is positively only one character which is absolutely distinctive of 
Passerine birds. That is, in the condition of the tendon of the 
patagialis brevis muscle as it was described some years since by 
the late Prof. Garrod’. Though. it is perhaps easy enough to 
define the Passeres by a combination of characters, none of these 
characters are everywhere present. It is therefore of more import- 
ance than in some easily definable groups to add to this single 
character only wanting in the Pseudoscines (Menura and Atrichia) 
another which future research may possibly show to be more 
universal, and which is at any rate found in several genera widely 
separated from each other. 
Fig. 3. 
Abdominal and thoracic viscera of Rook displayed by removal of 
abdominal muscles, 
St., stomach; Z., liver; O.S., oblique septa. The lobes of the liver are covered 
by a membrane continuous with the dorsal part of the oblique septa. 
This anatomical feature may therefore have a considerable 
systematic interest. Apart, however, from this, which requires 
still further proof, the conditions which obtain in the Passerine 
bird remind one in some degree of the Crocodile. The liver-lobes 
1 Coll. Papers, p. 356, 
