. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 264 INEZ L. FIG. 6. Ventral view of the poste- rior abdominal region of Desitiog- nathus briinleyonim, X 2- All of the abdominal muscles have been removed except the transversalis muscles and the vestigial ypsiloid muscles of the left side. Abbreviations not previ- ously explained : r>it median process of pubis ; ya,., vestige of anterior yp siloid muscle ; yp,, vestige of posterior ypsiloid muscle. arises from the lateral process of the pubis. From this origin the fibers diverge to their insertion mainly into t
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 264 INEZ L. FIG. 6. Ventral view of the poste- rior abdominal region of Desitiog- nathus briinleyonim, X 2- All of the abdominal muscles have been removed except the transversalis muscles and the vestigial ypsiloid muscles of the left side. Abbreviations not previ- ously explained : r>it median process of pubis ; ya,., vestige of anterior yp siloid muscle ; yp,, vestige of posterior ypsiloid muscle. arises from the lateral process of the pubis. From this origin the fibers diverge to their insertion mainly into the linea alba, although in most cases a few are inserted into the first myocomma. When we consider the Cartilago ypsiloidcs of the lunged forms, with its stem in the linea alba and its arms diverging at the first myocomma, it seems very probable that this muscle in the lung- less forms is a vestigial M. 'ypsiloidens posterior which persists even after the disappearance of the cartilage to which it was orig- inally attached. In some speci- mens a few fibers of this muscle were found to extend to the sec- ond myocomma and in one speci- men of Dcsmognatlius brimleyorum a separate little muscle (Fig. 6, jw) consisting of a few fibers only was found in the region of the second myotome arising in the linea alba and converging ob- liquely outward and posteriorly. These variable evidences of differ- entiation from the second myo- tome suggest, of course, the probable vestiges of the M. ypsi- loidens (Ulterior. Still further evidence of the for- mer existence of an ypsiloid car- tilage in lungless forms is fur- nished by the fact that in its absence the anterior portion of the M. pubo-ischio-femoralis interims originates from the linea alba in the exact region corresponding to the origin from the posterior part of the stem of the ypsiloid cartilage in lunged forms. 5. Cryptobranchus allegJieniensis. —In Cryptobranclms the ypsi- loid cartilage is very well developed and its articulatio
Size: 1523px × 1640px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
