THE CCKLOM 43 



more prevalent conditions. In the rook, however (fig. 28), 

 they are completely preserved. But the attachment of the 

 falciform ligament to the sternum in the median line is lost. 

 The cutting off of two lateral sections of the body cavity 

 by the oblique septa, and the division of the remainder by 

 the horizontal septum, do not, however, exhaust the sub- 

 divisions of that space. The liver lobes are attached, as is 

 so common among reptiles, to the oblique septa, in the 

 neighbourhood of the lungs, by what may be termed the 

 pulmo-hepatic ligaments. In making the comparison with 

 reptiles we assume for a moment the correctness of BUTLEK'S 

 contention that the oblique septa are in reality a portion of 

 the pulmonary aponeurosis, a view which will require a 

 careful re-examination. This ligament assists in closing 

 the pulmo-hepatic recess, which is really an extension forward 

 of the abdominal cavity, as shown by MALL'S instructive 

 figures of casts of the perivisceral cavity of birds. They are 

 narrow cavities, one on each side of the body, walled and 

 floored by the ligament mentioned, and by the oblique and 

 horizontal septa. The aperture of entrance has been com- 

 pared to the foramen of Winslow of the mammal, and so 

 named. In some birds there are no further complications of 

 the thoraco-abdominal coelom, but of others there are still 

 a few facts to relate before dealing with the homologies of 

 the various spaces and membranes. In the Australian pas- 

 serine StrutJiidea cinerea the liver lobes are each partitioned 

 into two by a transverse septum, which runs from the falci- 

 form ligament in the middle line to the oblique septum on 

 either side. This septum, which is clear and transparent, 

 does not actually divide the liver lobes ; it arches over each 

 with a free crescentic margin. In some other birds similar 

 septa are present, with very nearly the same relations. In 

 hornbills, cuckoos, and owls at any rate in some species 

 of each family -the two liver lobes are each completely 

 shut off from the ventral section of the abdominal cavity 

 (the ' subomental space,' as it has been termed) by delicate 

 partitions, of which one only, the left, is present in some 

 other birds, e.g. Chrysotis Gitildingi. The 



