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Show 1870.] MYOLOGY OK C H A M A E L E O N PARSONII. 861 External intercostals. These muscles seem to be formed by the internal oblique, from which they are undistinguishable. The internal intercostals are formed, as above said, by the transversalis. Rectus * (figs. 3 and 4, R). This muscle is interrupted by the ventral ribs, which its several portions connect together. Considered as one whole, it springs from the pubic symphysis, aud is inserted anteriorly into the posterior margin of the sternum, its anterior end being enclosed between the posterior origins of the two sternohyoids. The parts between the ventral ribs are with difficulty separable from the internal oblique, so that they might be regarded as thickened fasciculi of the mid-ventral portion of that muscle. The rectus anticus (fig. 5, R. A) is the only subvertebral muscle, there being no retrahentes costarum. It springs from the ventral aspect of the bodies of about the first 8 or 9 vertebrse, and it is inserted into the side of the occipital part of the basis cranii. Supracostalis (figs. 6 and 7, P. C). This is a fleshy band which passes upward and forward from the third sternal rib to the first elongated rib, which is in front of the first sternal rib. At its insertion it is conterminous with the most ventral part of the origin of the serratus magnus. The sterno-hyoid and sterno-thyroid have been noticed amongst the muscles of the hyoid. The pectoralis, latissimus dorsi, and sterno-coracoid will be described amongst the appendicular muscles. IV. MUSCLES OF THE TAIL. Supracaudal. The muscles which occupy the upper half of the caudal surface are the direct continuations backward of the longissimus dorsi. The continuation is direct, because the ilium does not divide them, but is superficial to them. The upper part (figs. 2 and 27, A) occupies the groove between the spines and zygapophyses, like the upper part of the longissimus dorsi. The lower part (figs. 2 and 27, B) occupies tbe groove between the zygapophyses and the transverse processes, like the lower part of the longissimus dorsi. These muscles are continued to the end of the tail. The ilio-caudal (figs. 2 and 27, II. C) seems to more or less continue backward the sacro-lumbalis, though it is not uninterruptedly connected with it, but springs from the sacro-iliac attachment and the hinder side of the sacral transverse process. It runs backward above, below, and between the caudal transverse processes, and is indistinctly subdivisible into two or more longitudinal muscles. It seems to answer to the ilio-caudal of the Urodela^. It runs * Meckel, I. c. p. 287. t See P. Z. S. 1860. pp. 268 and 46:1 |