77//; I'KJJ'JS. 11 



pubis and extends backwards. The same authority remarks that this 

 symphysis in the Cow has often a sahentcrest projecting into the pelvic 

 cavity, which, if it does not offer a very considerable obstacle to the 

 passage of the feetus, may nevertlieless greatly fatigue tlie obstetrist 

 when his hand is engaged between it and the young creature, during the 

 straining of the mother. 



Sheep and Goat. 



In these animals the ischio-puhic symphysis is rectilinear ; the inter- 

 posed cartilage is not ossified until very late in life, and almost never in 

 those which have had many young. The same remarks are applicable 

 to this symphysis in the Pig. 



Bitch and Cat. 



The symphysis in the Bitch and Cat scarcely ever ossifies ; so that 

 these animals, when advanced in age, still have a notable degree of 

 mobility in this region, and the diameter of the pelvic cavity may be 

 proportionately increased. 



Sacro-sciatic Ligament. 



The sacro-sciatic ligament (Fig. 4, d) transforms the pelvic cavity into 

 a complete canal, by filling up the space on the side of the pelvis, 

 between the sacrum and coxai. It is a wide membranous expansion, 

 composed of white fibrous tissue — -the fibres crossing each other in 

 different directions, and sei-ves rather to enclose this portion of the 

 pelvic space than to maintain the solidity of the sacro-iliac articulation. 

 It is irregularly quadrilateral, its superior border being rectilinear, and 

 attached along the rough crest on the side of the sacrum, as well as to 

 the first two or three coccygeal bones. Its anterior border is irregular, 

 and not well defined, but it is inserted above into the base of the 

 sacrum, and below into the inner border of the ilium, circumscribing in 

 its middle the opening which has been named thegi'eat ischiatic notcli, 

 through which the gluteal vessels and nerves, as well as the sciatic 

 nerves, pass, and to the compression of which against the bones of the 

 pelvis during pregnancy may be due cramp of the posterior limbs, 

 or even more or less persistent paralysis ; the inferior border is attaclied 

 to the spine of the ischium, as well as to the ischiatic tuberosity, and 

 between these insertions, and immediately behind the cotyloid cavity, 

 it forms the small ischiatic notch, the opening through which the 

 obturator internus muscle passes ; while the j^osterior border, not well 

 limited, completes the posterior circumference of the pelvic cavity, and 

 divides into two layers, between which lies the semimembranosus 

 muscle, and above it is mixed up with the enveloping sheath of the tail 

 muscles and bones. 



The inner face of this wide ligament is covered by peritoneum to the 

 extent of one-third in front ; and behind it is in direct relation with 

 various organs contained in the pelvic cavity, by means of an abundant 

 loosi- connective tissue. Its crtcrnal face is traversed by the sciatic 

 ner\-es and covered by muscles. 



There are no notable differences in this ligament in the various 

 species of animals we are dealing with. 



