Nos. IAND2.] ANATOMY OF SCOMBER SCOMBER. 227 



the muscle, not far from its hind edge, and, running upward and 

 backward, soon reaches the hind edge of the muscle, along which 

 it continues upward to the dorsal end of the muscle where it is 

 inserted on the postero-ventral dermal ray of the fin. A large 

 part of the muscle thus acts, directly, on this one ray alone. The 

 muscle, in contracting, gives to the rays a motion downward and 

 backward, in the plane of the fin, and also a motion laterally, at 

 right angles to that plane, its principal action being undoubtedly 

 the latter. 



This superficial muscle of the fin is, in the nomenclature adopted 

 by ]\IcMurrich in his descriptions of Amiurus (No. 49, p. 332), 

 the abductor superficialis. In the nomenclature adopted by 

 Klaatsch in his description of Polypterus (No. 44) it would seem 

 to be the extensor superficialis, but it is also, at the same time, a 

 depressor. According to the definition of angular movements 

 given by Thane (No. 61, Vol. II., Pt. II., p. 151) it would seem 

 to be mainly a flexor, but also an adductor. Wishing to avoid 

 the introduction of new names, pending more extended investi- 

 gations, it seems to me best, for the present, to call it, after Mc- 

 ]\Iurrich, the abductor superficialis. 



The next largest lateral muscle, in Scomber (Abdp), lies in- 

 ternal to the superficial abductor muscle, its postero-ventral edge, 

 however, projecting considerably beyond the corresponding edge 

 of the superficial muscle and thus having, in this part, an exposed 

 lateral surface. Its surface of origin occupies all of the lateral 

 surface of the procoracoid excepting only its dorsal edge, and all 

 of the lateral surface of the membrane that fills the large fenestra 

 between the procoracoid and the clavicle. Anteriorly and ven- 

 trally the surface of origin extends onto the adjoining lateral sur- 

 face of the mesial wall of the clavicle, and dorsally it extends onto 

 the adjoining lateral surface of the scapulare. Its fibers first 

 spread somewhat, from their points of origin, and then converge, 

 and, becoming tendinous, are inserted on the lateral eminences 

 on the proximal ends of the dermal rays, immediately internal to 

 the tendons of the superficial muscle. The tendinous distal end 

 of the muscle is, however, not as distinctly separated into separate 

 tendons as the corresponding part of the superficial muscle is. In 

 contracting, the muscle has much the same action upon the fin as 



