ARRANGEMENT OF THE FASCIA- OF THE PELVIS. 137 



ilix)- and pubo-coccygei muscles undergo to form the levator 

 ani. At the same time, the presence of a strong visceral 

 layer of pelvic fascia, obviously for purposes of support, which 

 extends between the viscera and the lateral pelvic wall, is 

 suggestive of another modification of structure to meet special 

 requirements. But whereas the homologous muscles of the 

 levator ani in man can usually be recognised without difficulty 

 in lower mammals, this is not the case with the visceral layer of 



I pelvic fascia. Apparently it does not exist as such in lower 1 

 mammals, and consequently it must be regarded as a new / 

 formation. 



In the orang-utan, the visceral layer of pelvic fascia is strongly 

 developed, and arranged very similar to that in the human 

 subject. One or two special features, however, seem to throw 

 some light upon and suggest some explanation of the more 

 complex and stronger fascia in man. In the orang the visceral 

 fascia is directed almost sagittally backwards, and extends along 

 the sides of the bladder, vagina, and rectum, from the symphysis 

 pubis in front to the posterior part of the pelvic cavity behind, 

 and in the latter situation it is continued over the internal 

 iliac vessels. The fascite of both sides, therefore, enclose a space 

 which is occupied by the pelvic viscera. It is interesting to 

 note that externally the layer springs from the upper surface 

 of the levator ani, along a line extending from the lowest part 

 of the symphysis jDubis towards the ischial spine, being directly 

 imited to the upper investing fascia of the muscle, and is not 

 attached to bone, except to a slight extent to the back of the 

 pubis in front. Its line of attachment externally presents no 

 special thickening to form a tendinous arch or ' white line,' 

 and this is in harmony with the observations of Kollmann on 

 the chimpanzee. In three specimens (two female and one male) 

 this observer failed to notice anything resembling the ' white 

 line ' of the pelvic fascia. Holl rightly points out that the 

 fascia visceralis arises from the upper fascia of the pelvic 

 diaphragm in man, and this is borne out by the lateral con- 

 nections and attachments of the fascia in the orang. 



From its lateral attachment, the fascia is directed, almost 

 immediately, transversely inwards, so that it lies, for a short 

 distance only, on the upper muscular fascia of the pelvic 



