SCHULTE, SKI WHALK. 423 



Pelvic musculature. The ischio-caudalis arises from the ectal surface of the pelvis in its 

 ischial portion by its mesal fasciculi, and far more extensively from the sheath of the rectus 

 lateral to the pelvis. It is a thin sheet-like muscle of triangular form, united in the midline 

 with its fellow of the opposite side by a narrow raphe. Its fasciculi are directed caudad and 

 mesad and are inserted into the tips of the chevron bones. The muscle extends to the junction 

 of the pedicle with the flukes, being the most superficial of the ventral muscles of the region 

 and covered only by the aponeurosis which continues the panniculus. The muscles are united 

 as far rostrad as the anus, where they diverge to give passage to the rectum. On its dorsum as 

 in Phoccena (Stannius) they are united by a firm aponeurosis. 



The levator ani arises from the ental surface of the pelvis and, caudal to the ischium, its 

 origin is continued from the deep surface and mesal border of the ischio-caudalis to which it 

 is united by a tendinous inscription. Its fasciculi pass to the midline almost transversely unit- 

 ing in a raphe with those of their antimere; where passage is given to the vagina and rectum, 

 the bundles of the levator are continued into their walls. 



The ischio-cavernosus is a relatively large muscle, superficial to the levator. It arises 

 from the mesal margin of the ischium and expanding slightly is inserted into the dorsum of 

 the clitoris, uniting with its fellow in a raphe. 



Intercostals. These muscles, of which there are twelve pairs on each side, were strongly 

 developed and characterized by the marked obliquity of their fasciculi. In other respects 

 their arrangement was as usual. The interval between the two proximal segments of the bifur- 

 cated first rib was occupied by mucle continuous with and having the direction of the scalenus. 



Diaphragm. This is a strong and compactly built muscle, in its sterno-costal portion 

 averaging somewhat more than 1 mm. in thickness. On its abdominal surface is a dense end- 

 abdominal fascia, upon which is a heavy layer of subperitoneal areolar tissue, the whole, dia- 

 phragm, fascia and areolar tissue measuring 2 mm. in thickness. The diaphragm in the ventral 

 midline arises from the linea alba and the ental layer of the sheath of the rectus between the 

 extremities of the ribs of the sixth pair. These fasciculi, the equivalent of the pars sternalis, 

 have a sagittal course and overlap the bundles of the pars costalis on their abdominal surface 

 so that there is no fibrous interval between these portions of the muscle. The pars costalis 

 arises along an oblique line extending from the tip of the sixth to that of the thirteenth rib. 

 Here it turns upon itself and the line of origin is continued in a dorso-rostral direction along 

 the ental surface and upper border of the last rib for the distal third of its length. These fasci- 

 culi are directed rostrad and dorsad having nearly the same inclination as the ribs from which 

 they arise, in this direction agreeing with the lateral bundles of the pars lumbalis with which 

 they are perfectly continuous. The pars lumbalis is composed of a crus laterale, crus inter- 

 medium and crus mediale. The latter arises tendinous from the bodies of the first two lumbar 

 vertebrae. The tendon of origin arches in front of the aorta immediately rostrad of the coeliac 

 axis. From this in its whole length arise fasciculi of a general sagittal direction and, with refer- 

 ence to the crus intermedium, of superficial position. The bundles of the right crus are com- 

 pacted into a ridge as they ascend and arch ventrad of the orificium oesophagi, forming a sharp 

 muscular falx to the right and in front of the aperture. Those of the left crus continue as a 

 flattened band upon the dorsum of the oesophagus and turning to the right reach the central 

 tendon. The remainder of the diaphragm arises from the sheath of the great hypaxial muscle, 

 which extends from the last rib throughout the lumbar region and the pedicle. The line of 



