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Show 1899.] THE MYOLOGY OF THE EDENTATA. 321 ment of a portion of the rectus ventralis. We have, however, very carefully examined the question and have come to the conclusion, from the facts that (i.) it so often continues the direction of the scaleni and (ii.) is occasionally connected to them by direct fibres, that the muscle should be looked upon as a caudacl extension of scalenus longus and that its presence is correlated with the fact, already insisted upon, that the last-named muscle has a very limited attachment in the costal region. In the Bradypodidce the muscle was noticed in five specimens of Bradypus (1, 3, 4, 5, 6); it was attached in all to the first rib anteriorly, but its posterior connections were various. In Cholcepus (10) it passed from the first and second ribs to the eighth and ninth. Amongst the Myrmecophagidce, we have no record of its occurrence in Myrmecophaga itself, but in Tamandua (14, 16) it is well marked and passes from the first to the seventh and eighth ribs; it was also present in four specimens of Cyclothurus (17, 19, 20, 21). In the Dasypodidce the muscle, for some reason not apparent to us, shifts its anterior attachment nearer to the mid-ventral line. Thus in Dasypus (22), as we have already mentioned, it is attached deep to the rectus ventralis, Avhilst in Tatusia (25) its anterior attachment is to the manubrium sterni. In Chlamydophorus (27) the muscle is very slender and feeble and is attached to the first rib. In another specimen of the same animal (28) Hyrtl does not allude to the muscle. Amongst the Manidce the muscle was found passing from the 1st to the 3rd, 4th, 5th, 6th, and 7th ribs in Manis (29). Its presence is not recorded in any of the descriptions of the Orycteropodidce, nor do Cuvier and Laurillard figure it in their plates of the myology of this animal (37). Recti capitis dorsales.-There does not seem to be any delami-nation, producing a r. c. d. medius, as is the case in so many mammals. W e find only records of r. c. d. superficialis et profundus (r. c. posticus major and minor), as in Man. Splenitis capitis et colli.-These muscles are subject to a good deal of variation in the Edentata and especially amongst the Bradypodidce. In Bradypus, a form possessing nine cervical vertebrae, we are not surprised to find the colli very large and the capitis either very small (1, 4, 6) or absent altogether (3). In one specimen (3) there were two splenii colli, the anterior arising from the spines of the 3rd, 4th, 5th, and 6th cervical vertebrae, while the posterior came from five spines behind these. In Cholcepus (10), a form in which the number of cervical vertebras is liable to reduction, the splenius capitis Avas large and rose from all the cervical spines or the ligamentum nuchas dorsal to them. The splenius colli was absent. Amongst the Myrmecophagidce there was no splenius colli in Tamandua (14) or Cyclothurus (21). In another specimen of the first-named animal (16) it went to the atlas only. Amongst the Dasypodidce there was no splenius colli in Dasypus (22, 24), Tatusia (25), or Chlamydophorus (27). In Manis (29) there is also no splenius colli, nor have Ave any record of the muscle in Oryeteropus. W e may sum up the description of |
