THE YPSILOID APPARATUS OF URODELES. 



265 



fork slightly anterior to the first myocomma and the lateral arms 

 extend obliquely across the third myotome. 



The musculature of the cartilage is interesting. Superficially, 

 the first myotome of the rectus abdominis is imperfectly differen- 

 tiated into two portions, and the medial fibers not only of the 



FIG. 7. Dissection of Cryptubranckus allegkeniensis showing the ypsiloid carti- 

 lage and the muscles associated with it, X 2^. The external oblique and rectus 

 abdominis muscles have been removed from the left side. Abbreviations as in 

 previous figures. 



first but of the second myotome are inserted into the stem of 

 the cartilage, the more anterior fibers of the second monotome, 

 however, being inserted into the ventral surface of the cartilage 

 at the very base of the arms. 



The deeper layers show a strongly developed M. ypsi- 

 loideus posterior, differing from that of the forms already de- 

 scribed in that its insertion into the Cartilage ypsiloides extends 

 only about two thirds the length of the arm, the thin, 

 expanded, outer third of the arm being free from all muscu- 

 lar attachment. The most medial fibers of the third myotome 



