THE MYOLOGY OF AIMURUS CATUS. 323) 
dorsal surface of the muscle. Opposite the second branchial arch a 
slip (HBr’) separates from the main muscle and is inserted into the 
inner extremity of the anterior ridge of ceratobranchial iii. A 
second slip (H Br’) is inserted similarly into ceratobranchial iv., the 
main muscle passing straight backwards to be inserted into the an- 
terior border of the pharyngeal inferior (ceratobranchial v.) In a 
specimen of Amiwrus nigricans (Les) Gill, fibres were also seen pass- 
ing from the main muscle to ceratobranchials i. and ii. Certain 
interarcual slips run parallel to the muscle proper, and, from their 
relation to the slips to the ceratobranchials, may be considered as sec- 
ondary parts of it. One (HBr?) arises from the point of attachment 
of the slip to ceratobranchial iii., and passes back to the anterior 
ridge of ceratobranchial iv., its insertion being closely related with 
that of slip from main muscle to the same bone. A second bundle 
(HBr*) continues this first one backwards, and is inserted into the 
inferior pharyngeal (ceratobranchial) along with the main muscle. 
Action.—The hyoid being fixed it will draw the branchial appara- 
tus forward, the interarcual slips approximating the arches to which 
they are attached. 
As indicated by the synonyms, the muscle under consideration is 
probably comparable to two or more distinct muscles in other T'eleo- 
ste. Tne main muscle seems to have certain analogies with the 
muscle in Perca, termed by Vetter the pharyngo-hyoideus, and by 
Owen the branchi-depressor, which extends from the urohyal to the 
inferior pharyngeals on either side. The pharyngo-arcualis, which 
is present in Hsox and the Cyprinoids (in which the pharyngo- 
hyoideus is absent), but absent in Perca, also presents resemblances. 
It arises from the anterior border of the inferior pharyngeal, and’ 
divides into two slips, the outer of which passes to ceratobranchial 
iv., and is, therefore, comparable to the interarcual slip extending 
between the same parts in Amiurus. The inner portion inserts into 
hypobranchial ii., uniting in Hsox with the obliqui ventrales of 
ceratobranchial iv. and hypobranchial iii. The first of these latter 
muscles in Hsox and the Cyprinoids sends a slip to the ceratohyal, 
and that of the fourth arch besides passing to its own ceratobranchial 
sends also a slip to the hypobranchial iii. 
I am inclined to consider the hyobranchialis of Amiwrus as equi- 
valent to all these parts. If one imagines the pharyngo-hyoideus of 
Perca, and the pharyngo-arcualis of Hsox and the Cyprinoids united, 
