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Show 292 MR. R. H. BURNE ON THE [Apr. 18, The ribs and the nuchal plate are embedded in the deep surface of the dense integumentary carapace. In a similar way, the dorsal parts of the dorso-lumbar region of the vertebral column are partially embedded in the deeper parts of the carapace as far back as the last ribs. The sacrum and tail are free. The sacral region had been injured by a spear-thrust and the surrounding parts were somewhat decayed, so possibly the freedom of the sacrum may have been artificial. T h e M u scular S y st em . The muscles of the trunk of a young animal have been described by Rathke*, and those of the shoulder in another small specimen by Fiirbringer f . As most authors, who have dealt with the muscles of Reptiles, have used different names for the same muscle, I have thought it best to adopt the names and numbers given by Hoffmann in Bronn's ‘ Thierreich ' (Bd. vi. Abt. iii.)-in the first place because they do not carry with them any implied homology with the muscles of mammals, and in the second place because a full synonymy is given with each name and the comparison with other descriptions is thereby very much simplified. An exception has been made in the case of the hind-limb muscles, for which Dr. Gadow's t names and numbers are used. Muscles of the Head and Keck. Squamoso-maxillaris (depressor maxilla:) (text-fig. 55. 11).- Origin : hinder edge of the squamosal. Insertion : ventral surface of the angle of the jaw. A cylindrical muscle with fleshy origin and insertion. Separated at its origin into two parts by the insertion of a slip of the mylohyoid. Dilator tuhce (text-fig. 55. 12).-Origin : squamosal, internal to origin of squamoso-maxillaris. Insertion: upon the external meatus. Testo-occipitis (text-fig. 55. 13).- Origin : the anterior part of the nuchal plate, close to the mid-line. Insertion: the hinder edge of the parietal, 2 cm. from the mid-line. A cylindrical muscle 2 cm. in diameter. Testo-capitis (text-fig. 55. 14).--Origin: the carapace, along a line that slopes outwards from the point of the first rib to the second. Insertion : the hinder margin of the skull between the insertion of the testo-occipitis and the origin of the squamoso-maxillaris. A very powerful muscle, with an extensive narrow origin. Cervico-capitis (text-fig. 55. 15).-Origin: the dorsal parts of # Rathke : Ueber die Entwicklung der Scliildkroten, 1848, p. 154. f Fiirbringer: " Zur vergl. Anat. der Schultermuskeln," Jena. Zeits. Bd. viii 1874, p. 221. J Gadow : " Beitr. zur Myologie d. liinteren Extremitat der Reptilieii," Morph. Jalirb. Bd. vii. 1882, p. 329. |
