THE MYOLOGY OF AMIURUS CATUS. 335 
2. AppucToR PRoFuNDUS PELVIS. 
This is seen on removing the preceding. It arises from the surface 
of the pelvis and from the septum, and is inserted below the preced- 
ing into the bases of the rays. 
Action.—Assists the preceding in abduction but does not separate 
the rays. 
, 
3. ABDUCTOR SUPERFICIALIS PELVIS. 
On cutting through the insertions of the ventral trunk muscles and 
bending back or removing the pelvis, the dorsal muscles are exposed. 
The superficial muscle does not cover the deep one as in the case of 
its ventral equivalent, but is of a triangular shape, expanding as it 
passes backwards and inwards to its insertion. It arises from the 
thickened outer edge of the pelvis ; its outer fibres pass directly back- 
wards, the inner ones backwards and inwards. It divides imper- 
fectly into a number of tendons, one being inserted into the upper 
surface of the base of each ray. 
Action.—Adducts the fin. The outer fibres also help to separate 
the rays. 
4. Appuctor Prorunpus PELVIS. 
Lies to the inner side of the preceding. It arises from the dorsal 
surface of the pelvis and from the septum. Its outer fibres are stout 
and quickly become tendinous, passing under the superficial muscle, 
the inner ones being longer. It is inserted into the bases of the rays 
below the add. superf. 
Action.—Aids the superficial muscle and also tends to approxi- 
mate the rays. 
Innervation.—The musculature of the pelvic fin is supplied by 
branches arising from a plexus formed by the union of' the rami vent. 
spinales, X., X1., Xii., xiii, and xiv. A plexus is first formed for the 
supply of the ventral portion of the musculature, but other branches 
are detached which form a similar plexus for the supply of the dorsal 
muscles. 
The arrangement of this portion of the musculature of Amiurus 
corresponds very closely with that described by Cuvier, Stannius, 
&c., the only marked difference being the limitation in size of the 
add. superf., which in Perca seems to cover more pertectly the add. 
