Proceedings of the Scientific Meetings of the Zoological Society of London 1869

Page 291

1869.] THE MYOLOGY OF MENOPOMA. 263 partly from the postero-ventral border of the last branchial arch*, partly from the fascia of the side of the neck behind the branchial archesf. Thence it descends to the middle line of the body beneath the trachea, and above the sterno-hyoid, which latter is superficial to it. Genio-hyoideusX (figs- 2 & 5, G. H). On removing the mylo-hyoidei, the two genio-hyoidei are seen running backwards (one on each side) from the symphysis of the mandible. Each genio-hyoid arises from the anterior part of the ramus of the mandible of its own side (more or less connected with the submentalis), and is inserted posteriorly into the fascia, which also receives the insertion of the constrictor faucium. The cerato hyoideus externus (figs. 2 & 5, C. II. E) is a con­siderable muscle which arises from the first branchial arch, and is inserted into the cornu of the hyoid towards its middle. The cerato-hyoideus internus (figs. 2 & 5, C. H. I) can hardly perhaps be reckoned a distinct muscle in Menopoma, in which it has a common insertion with the muscle last noticed. It arises, however, from the ventral segment of the second branchial arch. Constrictor arcuum (figs. 2, 3, & 5, C. A). This small band­like muscle arises from the first branchial arch, and is inserted into the last two branchial arches. Fischer says§, no doubt correctly, that the muscle consists of two layers, the superficial one being inserted into the last branchial arch, and the deeper layer into the penultimate branchial arch. This muscle overlaps and binds down the constrictor faucium. The adductor arcuum (figs. 3 & 5, A. A) is a very small muscle, arising from the fascia on the ventral surface of the sterno-hyoid. Passing upwards and outwards, it goes to the last branchial arch. Sterno-hyoideus (fig. 2, St. II) A considerable muscular mass, which may conveniently be distinguished by this name|], though in fact it is the anterior termination of that great ventral muscular mass which consists of the united internal oblique and rectus. Its insertion is into the posterior part of the under surface of the basi­hyal and the adjacent parts of the ventral segments of the branchial arches. The antero-internal portion of the ventral part of each sterno­hyoid shows a slight indication of distinctness as a muscular fasci­culus inserted into the fascia into which the genio-hyoideus is inserted. This appears to represent, in a rudimentary manner, the distinct muscle named levator maxillae inferioris brevis by the Dutch authors •*![. * The hyo-trachealis of Fischer, I. c. p. 92. t The dorso-trachealis of Fischer, I c. p. 92. j The levator maxillee inferioris longus of Schmidt, &c, see I. c. p. 29, pl. 6. fig. xiii. 5. § L. c. p. 75, and tab. 4. fig. 2, ca. || It is so by Dr. Fischer, see I. c. p. 104, and tab. 4. fig. 2, sh. It is the cerato-hyoideus of the Dutch authors, Schmidt &c, see /. c. p. 30, pl. 6. fig. xiii. 9. •J[ See Schmidt &c, p. 30, and pl. 6. fig. xiii. 6.