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. 
IIJ.—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. 
TX.—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 mandibule. Behind, it is 
attached to the descending ridge of the supraoccipital, 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 premaxille. On 
removing this fascia one exposes the 
1. Appucror ManpisuLa, (No. 20, Cuv.; Retractor oris, Owen ; 
M. Masseter, Ag.) (Pl. 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- 
