128 DR PETER THOMPSON. 



The muscular set of fasciae are most easily and with greatest 

 advantage studied in animals where the levator ani is replaced 

 by a more primitive group of muscles, as in carnivores. In 

 Fdis leopardus and HerjJcsfes mungos the following fasciffi are 

 clearly recognisable, (a) the obturator fascia covering the 

 obturator internus, and {h) the fascia covering the ilio-coccygeus 

 and pubo-coccygeus, — the homologous muscles of the levator ani. 



In these representatives of the carnivora, the obturator fascia 

 is a distinct layer of connective tissue covering the inner surface 

 of the obturator internus, though it is neither so well developed 

 nor so fibrous as the corresponding structure in man., In both 

 carnivores it has practically the same attachments as the muscle, 

 and as the latter is much less extensive than in man, the fascia 

 only covers a part of the lateral wall of the pelvis. It reaches, 

 in front, to the back of the pubis ; behind, to the great sacro- 

 sciatic foramen ; below, to the conjoined rami of the pubis and 

 ischium ; and above, as high as a horizontal line drawn from the 

 upper part of the symphysis pubis to the ischial spine. "" It is of 

 uniform development, and differs from the corresponding fascia 

 in the human subject in that the ilio-coccygeus muscle does not 

 take origin from it, but extends upwards as high as the 

 ilio-pectineal line.^ 



"^-The fascia covering the flexor group of tail muscles (ilio- 

 coccygeus and pubo-coccygeus) is not so obvious as the preced- 

 ing; indeed, it is usually thin and unimportant. It covers both 

 the inner and outer surfaces of the muscles, and the two layers 

 are continuous round the free mesial border of the pubo- 

 coccygeus and in the intervals between the constituent elements 

 of the muscular mass. It is convenient to refer to this fascial 

 investment as the fascia ^ ilio-coccygea and the fascia pubo- 

 coccygea, and in each to distinguish two layers — an inner 

 and an outer. -''At the pelvic wall they are attached to the ilio- 

 pectineal line and the pubis, and internally fuse with the fascia 

 of the tail. 



In the majority of mammals the ilio-coccygeus and pubo- 

 coccygeus are similarly disposed, and it seems probable, therefore, 

 that a corresponding arrangement of the fascial layers would 

 usually, if not invariably, be found. But in man and the 

 orang-utan, in both of which the two primitive muscles have 



