260 



INEZ L. WHIFFLE. 



of the pubis, its thickest portion having its origin in the lateral 

 process. The fibers of this muscle diverge slightly, and are in- 

 serted into the edge of the lateral arm, and the inner (/. c\, dor- 

 sal) surface of the stem of the Cartilago ypsiloides. Lying, as it 

 does, dorsal to the main mass of the rectus abdominis, this mus- 

 cle is almost continuous at its lateral boundary with the obliquus 



internus. It is the muscle which 

 has been often called the pyramid- 

 alis. Thus Hoffmann described it 

 as a part of the general urodele 

 musculature and homologized it 

 with the pyramidalis of human 

 anatomy. 



The other ypsiloid muscle, M. 

 ypsiloidciis anterior {yd}, arises from 

 the medial portion of the second 

 myocomma, and from the linea 

 alba of the first metamere, and its 

 fibers extend obliquely outward 

 and posteriorly to their insertion 

 into the anterior edge of the lateral 

 arm of the cartilage. 



The transversalis muscle shows 

 a wide range of individual varia- 

 tion in its relation to the ypsi- 

 loid cartilage. In some of the 

 specimens dissected none of its fibers were inserted into the car- 

 tilage. The posterior narrowing of the aponeurosis of the trans- 

 versalis in this region, however, causes the edges of the aponeu- 

 rosis to lie closely parallel with the outer edges of the ypsiloid 

 cartilage, and in the majority of the specimens dissected some of 

 the fibers of this muscle had become inserted into the cartilage, 

 the ends of the lateral arms being the region where this insertion 

 most frequently occurs. The extent of the insertion of this 

 ypsiloid portion of the transversalis varies, however, from one 

 which involves the outer portion of the arm only, to one which 

 extends along nearly the entire length of the cartilage, both arm 

 and stem (Fig. 3, tb}. Almost invariably a few fibers of the 



FIG. 2. Ventral view of Diemyc- 

 tylus vtridesce>is,-posle.r\or abdominal 

 region, X 3- All of the abdominal 

 muscles have been removed except 

 the tranversalis muscles and the yp- 

 siloid muscles of the right side. 

 Abbreviations not previously ex- 

 plained : /, M. transversalis abdom- 

 inis ; _)'/, M. ypsiloideus posterior. 



