COPULATORY ORGANS OF THE AMNIOTA. 
19 
the rectum by a thin but high circular fold, and against the cloaca by a high and 
thick semi-lunar fold coming down from the dorsal wall. The cloaca forms a dorsal 
recessus, into which open the oviducts ; this sometimes common ostium is provided 
with a strong sphincter, which is in connexion with the fold just described. The 
ureters open side by side in one common slight niche on the dorsal side, towards the 
caudal margin of the anus ; the small lips of the niche can close this little chamber. 
In the male snakes the ureters and vasa deferentia of each side are commonly united. 
A peculiarity of the Ophidia is, therefore, the separate and independent position of 
the oviductal orifices. The whole cloaca is, although imperfectly only, divided by 
horizontal or oblique dorso-lateral folds into a dorso-internal or urino-genital and a 
ventri-external or faecal chamber—an arrangement similar to that of the Lizards, 
The latter chamber represents, of course, the vestibulum ; it receives in its posterior 
dorsal wall the penes, and on the lateral side of them the well-developed anal glands. 
In the female the representatives of the penes are frequently very small, and reduced 
to mere shallow invaginations of the postanal wall, but the anal glands are developed 
much stronger than in the male, and fill up the whole space otherwise occupied by the 
male organ. Like in the Lizards, only still more completely, the rectal chamber 
retains both faeces and urine, acting therefore as a cloaca. 
The cloacal arrangement of Halteria (figs. 12 and 13) represents a type by itself, 
which, however, bears resemblance to that of the Lizards. 
The transverse anal slit is bordered by non-prominent lips, and leads into a rather 
deep triangular chamber, which is lined by the continuation of the invaginated outer 
skin. In this chamber are seen three deep holes, viz., in each of the outer corners the 
openings of the anal glands, which have been accurately described by Dr. Gunther. 
They are of double the size of a common pea, and in the living animal have a strong, 
rather agreeable smell of musk and violets ; the middle hole is round, and can be 
completely closed through the contraction of the M. transversus medianus. Its walls 
seem to possess thick lips ; when cut open there is, however, only a very thin, 
although high, fold, which passes gradually into the lining of the cloaca, and contains 
no muscles. This fold is not clearly represented in any other reptile, although 
indications of it exist in many Lizards. The total absence of copulatory organs in 
Hatteria suggests that during copulation this circular fold can be protruded by 
inward pressure of the cloaca in order to secure conception. It would then bear a 
striking resemblance to the arrangement found in the Coecilia (cf. p. 27). This hole 
leads into another chamber which in a half-grown female was 7 mms. long ; its walls 
are lined with mucous membrane thrown into slight longitudinal folds. Inwards, 
towards the pelvic end, this chamber is bordered by another fold ; this is circular, 
thick at its base, thinner at its free margin, and towards the dorso-median line it is 
raised into a triangular or conical flap, which is about 5 mms. high, and fits into the 
opening of the bladder in the opposite ventral wall. This fold corresponds to the 
fold F of other Reptiles. The next chamber is wider and longer and of the same 
D 2 
