1 4 
DR. H. GADOW ON THE CLOACA AND ON THE 
skeletal and also from non-striped muscles. How such involuntary muscles can be 
separated off from the longitudinal muscularis of the intestinal canal is shown, besides 
by the M. levator of Ornithorhynchus, by the Crocodilia. There is in Alligator 
(figs. 3-5) a broad, rather double band of non-striped muscle, which, near the place 
where the ureters enter into the cloacal wall, leaves the latter, perforates the voluntary 
M. transversus cloacae, and firmly attaches itself to the fascia which covers the 
M. ischio-caudalis, rather near the medio-ventral line. There can be little doubt that 
this muscle is an additional protractor or shortener of the cloacal chamber, and helps 
to bring the copulatory organ to the surface. 
II. The Nerve-Supply of the Cloacal Region. 
The lumbar and sacral plexus of the Reptiles has been described and figured in the 
‘ Morphologisches Jahrbuch,’ vol. 7, but without reference to the plexus pudendus 
proper. 
In Alligator mississipiensis (fig. 3) the primary sacral nerve S is as a rule the 
twenty-sixth spinal. The obturator nerve is composed of ——, whilst the ischiadic 
plexus is formed by the greater portion of a, the entire stem S, and a considerable 
part of a, which is the first postsacral nerve, a sends out the following branches :— 
1 . Several strong branches to the powerful M. caudi-femoralis, which receives further 
on a similar supply from /3 and y. 2 . A long nerve which passes to (cf p. 10) the 
caudal margin of the symphysis ischium, and then supplies a portion of the M. rectus 
lateralis, the M. transversus lateralis s. medianus, i.e., the striped muscles of the anus. 
3. Several entirely cutaneous branches are distributed over that region. 
ft and y supply, like the other caudal spinal nerves, the M. caudi-ischiadicus ; the 
share of /3 in this is, however, very small. 
The stem /3 receives a branch from y and from a, through which combination a sort 
of individually most variable plexus is formed ; it supplies with several branches the 
muscles of the dorsal and of the lateral wall of the urinary chamber, and, moreover, the 
penis or clitoris, and lastly through many ramifications the rest of the whole cloacal 
vestibulum s. proctodseum. 
The sympathetic system is arranged as follows —In the lumbo-sacral region down 
to a. it is very regularly composed of metameric ganglia, rami communicantes, &c.; 
the peripheral branches supply the testes, kidneys, blood-vessels and the gut; no 
changes regarding the nervous system are visible at the level of e, the fifth presacral 
nerve, at about which level the ileum passes into the rectum. 
A remarkable change, however, takes place at a. The usual ganglion is somewhat 
removed from the stem on to the lateral chain, and numerous nerve branches are sent 
to the intestinal wall. In level of /3 all this is changed. The sympathetic system is 
reduced to a paired chain, composed of very thin rami communicantes sent from 
/3, y, 8, &c. There are no ganglia visible, and the chain supplies merely the caudal 
