266 



INEZ L. WHIFFLE. 



extend as a small bundle from the third myocomma to an inser- 

 tion into the middle of the ventral surface of the lateral arm of 

 the cartilage. This differentiation from the third myotome is the 

 only representative of a M. ypsiloides anterior, and except for its 

 insertion it is not at all distinct from the adjoining fibers of the 

 myotome. 



None of the fibers of the transversalis are inserted into the 

 ypsiloid cartilage. The edges of its aponeurosis in this region, 

 however, are parallel with the cartilage and separated from it by 



a space about equal to the 

 width of the cartilage itself. 

 Moreover, the stem and proxi- 

 mal third of the arms of the 

 cartilage are firmly bound to 

 the aponeurosis ; the portion 

 of the cartilage involved in 

 this attachment is much 

 thicker than the free, distal, 

 expanded region of the carti- 

 lage which lies in the third 

 myotome in a sort of sheath 

 between the aponeurosis of 

 the transversalis and the deep- 

 er layers of the rectus abdo- 

 minis and has neither muscu- 

 lar nor aponeurotic attach- 

 ments. 



The origin of the anterior portion of the M. pubo-iscliio-fenw- 

 ralis interims does not involve the ypsiloid cartilage, although it 

 extends to the extreme anterior margin of the pubo-ischium. 



It should be mentioned in connection with this description of 

 Cryptobranchus allegheniensis that Hyrtl ('65) has described the 

 ypsiloid cartilage of Cryptobranchus japonicns as lacking bilateral 

 symmetry in that the right lateral arm is subdivided into three 

 branches while the left is simple. This description was, I suppose, 

 based upon a single individual and the condition was quite prob- 

 ably an abnormal one. 



FIG. 8. Dissection of Nectitrus macu- 

 lalus showing a ventral view of the pelvic 

 region, with the M. pitbo-ischio-femoralis 

 extern us of the left side removed, X * 

 Abbreviations as in previous figures. 



[From an unpublished drawing by H. 

 H. Wilder.] 



