G 
IJR. H. GADOW ON THE CLOACA AND ON THE 
construct a special house to keep alive, and in a healthy condition, a considerable 
number of Reptiles of all orders. 
The study of fresh material possesses great advantages over that of preserved and 
diseased specimens, especially though if the anatomical results can be checked by 
observation of the functions of the organs. 
For a specimen of Siphon ops annulatus I am indebted to Dr. A. Gunther, for some 
of the Alligator embryos to Professor W. K. Parker. Struthio embryos had been 
collected by Mr. Sedgwick, aided by a grant from the Royal Society. Several well- 
preserved Ornithorhynchus and Echidna Mr. Sedgwick kindly put at my disposal. 
Adult specimens of Struthio, Rliea, Casuarius, and Apteryx belonged to the 
museum of the University of Cambridge, and came for the most part from the 
Zoological Garden, in London. In connexion with these investigations turned up 
several questions concerning the Cloaca, which suggested a comparative treatment of 
the whole cloacal region and of the copulatory organs throughout the Amniota. 
Of Reptiles the following material was at my disposal :— 
# Alligator 
Several embryos and several fresh specimens of about 
mississipiensis. 
5 feet in length, 
Crocodilus palustris. Several baby sjiecimens. 
Crocodilus acutus. About 3 feet long. 
*Crocodilus biporcatus. Numerous fresh specimens from 8 inches to 24 inches in 
length. One specimen of about 3 feet. 
Crocodilus vulgaris. Male copulatory organ of adult; specimen in R.C.S. 
Crocodilus sp. ? 
Monitor indicus. 
# Lacerta ocellata. 
# Lacerta viridis. 
Half adult female; preparation in the Cambridge Museum. 
Numerous specimens. 
Numerous specimens. 
Psammosaurus scincus. 
# Hatteria punctata. Male and female. 
# Tropidonotus natrix. Numerous specimens. 
Pelophilus madagascariensis. Male and female. 
# Testudo grseca, 
# Emys europrea. p Numerous specimens. 
# Clemmys caspica. 
There is an abundant literature on this subject, but the descriptions and conclusions 
found in it frequently agree neither with each other nor with the actual facts. A 
discussing review of the literature would lie beyond the scope of this paper. 1 
append, however, a list of the papers which I have consulted.. 
* The species marked with an asterisk were, or are, kept in the Reptile-house. 
