312 PROCEEDINGS OF THE CANADIAN' INSTITUTE. 



parison with other forms when no authority is given for statements 

 regarding these, it may be assumed that they are drawn from Vet- 

 ter's paper. 



I shall divide the various muscles into the following groups, ac- 

 cording to their present relations : — 



I. — Mandibular Muscles. 

 II. — Muscles of the Palatine arch. 

 III. — Opercular Muscles. 

 IV. — Muscles of the Hyoid arch. 



V. — Muscles of the Branchial arches. 

 VI.— The Trunk Musculature. 

 VII. — Muscles of the Pectoral arch and fin. 

 VIII. — Muscles of the Pelvic arch and fin. 

 IX. — Muscles of the Dorsal fin. 



X. — Muscles of the Anal fin. 

 XI. — Muscles of the Caudal fin. 



I.— MANDIBULAR MUSCLES. 

 In removing the integument from the side of the skull, one ex- 

 poses a strong fascia, attached above to the frontal and supraoccipital 

 bones, and covering the large adductor mandibulce. Behind, it is 

 attached to the descending ridge of the supi-aoccipital, and thence 

 passes to the posterior border of the hyomandibular, preoperculum, 

 and quadrate, whence it is continued on to the mandible. In front 

 it contains behind the eye the chain of infraorbital bones. Passing 

 below the eye, it passes forward and is attached to the antorbital pro- 

 cess, continuing on over the nasal region, and containing the nasal 

 and adnasal bones, to be finally inserted into the premaxillse. On . 

 removing this fascia one exposes the 



1. Adductor Mandibulce, (No. 20, Cuv.; Retractor oris, Owen ; 

 M. Masseter, Ag.) (PI. III., Fig. 1, AM.) 

 This is a broad thick muscle, which fills up the depression 

 on the side of the skull. It arises from a semicircular ridge 

 commencing anteriorly and above on the outer edge of the ecteth- 

 moid, extending thence along the frontal and supraoccipital. 

 The muscle covers the sphenotic and pterotic, from the edges of 

 which fibres also originate. Descending posteriorly, the line of origin 

 passes along the posterior edge of the hyomandibular and preopercu- 



