1896.] MR. F. FE, BEDDARD ON DISSURA EPISCOPUS. 231 
This state of affairs I have found in certain Hornbills and in many 
Owls. At present I have not surveyed the principal groups 
of birds from this point of view ; but some years since I described 
the same thing in a Penguin. Apart from this latter instance, 
which I hope to have the opportunity of re-examining, it is 
interesting to find a likeness between the Passeres and the Picarian 
birds, and between both and the Owls. 
As to the homologies of this structure outside the Class 
Aves, I am inclined to liken it to what Mr. G. W. Butler 
has termed the “ post-hepatic septum” in the Teiide. This 
structure, with which I am perfectly familiar from my own 
dissections, is a transverse septum which is attached to the ventral 
parietes, and nearly completely shuts off the liver-lobes from the 
rest of the abdominal cavity. In the Iguanide (Iguana, Metopoceros, 
Phrynosoma) there is apparently a trace of this post-hepatic 
septum in the shape of a membrane of limited extent which arises 
from the end of the right lobe of the liver, and is attached to the 
lateral parietes, forming thus a pocket shutting off the lung 
of that side of the body, In the Crocodile the membrane 
covering the liver, which represents a portion of the oblique septa, 
is reflected below the liver and separates it from the adjacent 
stomach ; this is probably to be also looked upon as a repre- 
sentative of the structures mentioned. 
5. A Note upon Dissura episcopus, with Remarks upon the 
Classification of the Herodiones. By Franx HE, 
Brepparp, M.A., F.R.S., Prosector to the Society, 
Examiner in Zoology and Comparative Anatomy to 
the University of London. 
[Received January 13, 1896.] 
As is well known, one of the main points of difference between 
the Ciconiide and the Ardeide is that the former possess the 
ambiens muscle, while the latter donot. But the late Prof. Garrod 
pointed out to this Society’ some years since that this general rule 
is not without exceptions; for in Xenorhynchus senegalensis and 
Abdimia sphenorhyncha he discovered that the muscle so typical of 
the Storks was absent. Another point of difference between the 
Storks and the Herons is in the structure of the syrinx; in the 
Storks this modified region of the windpipe curiously resembles 
the syrinx of the tracheophone Passeres, while the Herons have a 
perfectly: typical tracheo-bronchial syrinx. I found myself some 
years ago” that Xenorhynchus senegalensis, and more especially 
Abdimia sphenorhyncha, offered some points of likeness to the 
Herons in the structure of their syringes, which appeared to me 
to have some significance when correlated with the muscular 
peculiarity already referred to, In Abdimia (¢f. fig. 2, p. 233), 
1 “Note on an Anatomical Peculiarity in certain Storks,” P. Z.8. 1877, p. 711. 
2 “On the Syrinx in certain Storks,” P. Z. §. 1886, p. 321. 
