314 MR. W. A. FORBES ON THE [Apr. 17, 
In Larus I found the bursa represented by a small pouch. In 
the young Uria troile it is large and sac-like, and slightly curved 
from side to side (see fig. 2, p. 310). The walls are very glandular, 
and so thick that the central cavity is but small. There are no 
crests. In an adult Alea torda it was reduced to a pore-like opening. 
In none of the Tinami that I have dissected have I found any bursa ; 
on the other hand, the posterior wall of the third cloacal chamber 
is covered with numerous glands arranged in a tree-like manner. 
In all the birds hitherto mentioned (with the exception of Plotus) 
the bursa, as we have seen, opers by a more or less constricted 
aperture into the general cavity of the cloaca. In the Struthious 
birds, however, the very opposite is the case. The cloaca (or at 
least as much of it as corresponds to the first and second chambers 
opens into the bursa Fabricii. This will perhaps be best explained by 
looking at fig. 4, p. 313, representing the cloaca and bursa of a not full- 
grown Cassowary (Casuarius uniappendiculatus) from behind. The 
bursa is, as one sees, a large, somewhat triangular sac, attached above 
by a broad riband-like muscle to the posterior wall of the alimentary 
canal. Most of the back wallof the bursa has been cut away (a), to show 
the opening into its cavity of the cloacal chamber (4), out of which 
a pointer (d’) is seen passing up into the rectum above through the 
recto-cloacal valve. From this, I think, it will at once be evident 

Vent of young Emu (Dromeus nove-hollandig) with the parts still in situ, 
viewed from the outside. 
A. External sphincter. B. Cavity of bursa. ©. Wall of cloaca. D. Opening 
of cloaca into the bursa. H. Clitoris. EF. Glandular pores. 
that the cloaca does not open directly to the outer surface, but indi- 
rectly through the bursa by means of its large posterior and inferior 
aperture 6. A similar condition of things is seen in fig. 5, in a young 
Emu (Dromeus nove-hollandie)—where the parts are undisturbed 
