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Show 854 MR. ST. GEORGE MIVART ON THE [Dec. 6, mass which arises from the basihyal within the cup-like cartilaginous expansion of the lower end of the anterior cornu. Passing upwards in front of and within the posterior cornu, it is inserted into the summit of the latter. A muscle, which can only improperly be termed tbe genio-glossus, (fig. 7, G. G.), springs from the inside of the anterior part of the mandible, but posterior to the origin of the cerato-mandibular. Passing backwards, it meets its fellow of the opposite side at the hinder end of the dorsum of the tongue. Sterno-hyoid* (figs. 1, 3, 6, and 7, S. H). This arises from the sternum, between the sternal ends of the second and third sternal ribs, coming out, as it were, from a little muscular pouch formed on the inner side by the anterior end of the rectus, and on the outer side by fibres of the internal oblique, or external intercostals. Passing forwards and broadening, it is inserted into fascia closely connected with the ventral surface of the basihyal, opposite the insertion of the genio-hyoid. The sterno-thyroid^ (figs. 6 and 7, T. Hi) springs from the sternum, and, expanding anteriorly, is inserted into the summit of the thyro-hyal. As it passes forward it is embraced externally by the omo-hyoid, which dips in between it and the sterno-mastoid. Omo-hyoid J. This is an exceedingly slender and delicate muscle (figs. 6, 7, and 13, 0. II.), which is so bent upon itself that, while its hyoidean portion runs upward and forward, its scapular part runs upward and backward, the bend taking place where it passes beneath the sterno-mastoid. The muscle is thus an elevator of the hyoid, instead of, as is generally the case, a protractor. It springs from the upper anterior part of the basihyal, close to the insertion of the sterno-hyoid. Passing upward outside the sterno-thyroid, it dips in between the latter and the sterno-mastoid. It then passes superficially to the deltoids and lower part of levator claviculae, and is finally inserted into the outer surface of the scapula, just between the summit of the anterior suprascapular and the insertion of the levator claviculse. III. MUSCLES OF THE TRUNK. Longissimus dorsi (figs. 1 and 2, If and L2). This muscle exceedingly large in Parson's Chameleon, much larger, relatively as well as absolutely, than in the common Chameleon. The large development of this muscle might be anticipated from an examination of the skeleton ; for not only are the neural spines, much prolonged, but the articular processes (zygapophyses) are so produced as to simulate (if they are not rather homologous with) the metapophyses of the Mammalia. This large muscular mass is pretty clearly divisible into a larger upper and a smaller inferior portion. * Cuvier, /. c. p. 532; Meckel, 1. c. p. 136. t Cuvier, I. c. p. 532; Meckel, /. c. p. 130. \ Cuvier, /. c. p. 532; Meckel, 1. c. p. 13(5. |