CLOACA—COACHW=HIP-BIRD gI 
that of the rectum proper. In Struthio this chamber is followed 
by another, which is smaller and less defined, resembling in this 
respect some Saurians. 
It follows from the arrangement described above, that in Birds 
the urine is not retained in the small urodeum, 
but that, as in Saurians, it passes into the next 
chamber above. Through this the feces pass ; 
if they are very fluid, they collect in the then 
very capacious space, together with the urine, 
and transform the chamber into a physiological 
cloaca. If the feces are more solid, as for 
instance in Geese, they are retained in the 
rectum proper, and simply pass through the 
cloaca. In the Ostriches defecation and 
micturition are mostly separate acts, especially 
when the largely-developed and persistent bursa 
Fabricii acts as a physiological bladder, A  — Drscram or re 
true urinary bladder, i.e. a ventral dilatation of — CX°*®* °F * BiBP. 
the urodzum, is absent in Birds. tbl Cane - 
The copulatory organ in the male, and the Urodeum; P.D. Procto- 
corresponding part in the female, are developed d#um; 2. Rectum; u. 
é ureter; v.d, vas de- 
from the ventral wall of the vestibulum or  ferens. 
“»roctodeum.” It is present in two different 
forms. In the Ratitz, except Rhea, it,consists of a right and left 
united half, with a deep longitudinal furrow on the dorsal side, and 
strongly resembles the same organ in Crocodiles and Tortoises ; it can 
be protruded and retracted by special muscles which in the Ratite 
are partly attached to the pelvic bones. In Rhea, and among the 
Carinate in the Anseres only, the copulatory organ consists like- 
wise of two halves with a longitudinal furrow, but is greatly special- 
ized by being spirally twisted and being reversible like the finger 
of a glove ; its muscles are derived solely from the sphincter muscle 
of the vent. In other Carinate, for instance in the Tinamide, 
Cracidx, in Platalea, Ciconia, and Phcenicopterus, the penis is much 
smaller and simpler in structure, with all the appearance of a 
degraded organ. In the majority of Birds, especially in the highest, 
it has disappeared, and the primitive way of everting the cloaca is 
resorted to during copulation (H. Gadow, Phil. Trans, 1887, 
p. 32). 
COACHWHIP-BIRD, so called in eastern Australia from its 
loud full note, ending sharply like the crack of a whip, the Psophodes 
crepitans of ornithologists, while a second form, P. nigrigularis takes 
its place further westward. Beside this curious utterance it has a 
low, inward, melodious song. It inhabits the thickest brushwood, 
seldom exposing itself to view; but when seen is very animated in 
