22 
DE. H. GADOW ON THE CLOACA AND ON THE 
by the assumption that the ventral portion of the original chamber U D has been 
developed and partly shut off from the rest. Through the development of such a 
sinus urino-genitalis, the separation into a ventral or urino-genital-copulatory, and 
into a dorsal or faecal portion of the “cloaca,” is introduced, although imperfectly. 
At any rate there is no longer any retention of urine and of faeces in one common 
chamber : micturition and defaecation have become separate acts which exclude each 
other. Cf also p. 11. 
Paired anal pouches (cloacal bladders, anal sacs, &c.), opening by wide apertures 
into the dorsal wall of the cloaca opposite the urino-genital sinus, are present in the 
amphibiotic Emydes and in the more aquatic Chelydae, but absent in the terrestrial 
Chersidae and in the marine Cheloniidae, which latter have their feet transformed 
into fins. In most Mud Tortoises (Trionychidae) they seem likewise to be absent. 
Hoffmann, however, found them in a male T. cegyptiacus, but not in a female T. sinensis. 
These pouches are so placed that they can be compressed by the abdominal muscles 
and by the retraction of the hinder extremities, indirectly also through a peculiar 
mechanism in connexion with the M. lumbo-caudalis. Their walls possess often a 
considerable layer of circular and longitudinal non-striped muscles ; their inside is 
sometimes villous, mostly smooth, but never glandular. The orifices of these pouches 
can be brought into direct communication with the cloaca, to the complete exclusion 
of all other openings, except the external anus (Anderson). 
Anderson, and Bridge follows him, considers them as the “ structural equivalents ” 
of the anal musk-glands of the Crocodilia, but he adds that he “ never particularly 
observed that the Chelonia possessing these pouches are more characterised by a 
peculiar odour than the pouchless forms.” They frequently yield a yellowish 
grumous substance, most especially abundant in those forms w T hich have these 
bladders provided with villi (Platysternum). This comparison is erroneous, as 
already Duvernoy has pointed out; the pouches are certainly not glands, and are 
developed from the middle portion of the cloaca, whilst the organs of the Crocodiles 
are skin glands, like those on the throat. 
It has been known, since Townson, that some Chelonia draw w r ater into the cloaca 
per anum. He put an Emys into coloured water, and observed that, when put after¬ 
wards into clear water, it vented coloured water. He concluded from this that water was 
pumped into the anal pouches, and that the latter served for hydrostatic purposes. 
This view has been generally accepted, and is strengthened by the fact that neither 
the true terrestrial Tortoises nor the marine Turtles with their specialised flippers 
possess such additional hydrostatic organs. 
It was, however, apparently never ascertained if the pouches, and not only the 
cloaca, were filled with water. Anderson, with his great experience of Tortoises, 
remarks expressly that, although he had examined, immediately after death, nearly a 
hundred individuals of South Asiatic Emydes, yet in no instance had the cloacal 
