ORDEE. 



ACANTHOPTERI. 



This order embraces a large number of fishes having either one, two, or three dorsal fins. 

 In the case of one dorsal fin being present, its anterior portion is always composed of inarticu- 

 lated and undivided spiny rays, whilst the remaining portion consist of soft, articulated, and 

 often divided or bifurcated ones. When two dorsals exist, the anterior is spinous, and the 

 posterior soft. The ventral fins are mostly near the pectorals, being situated beneath or 

 anteriorly to the base of these latter fins, and whenever fully developed, they are composed of 

 an external, inarticulated, sjiiny ray, and rarely more than six articulated and branched ones, 

 the latter being generally five in number, and occasionally less. The swimming bladder is 

 without air duct to the throat. The inferior pharyngeals exist throughout as independent 

 bones. 



Family PERCIDAE, Bonap. 



The percoid or perch family has always been looked upon as typifying best the order of 

 acanthopterians at the head of the osseous fishes. 



It comprehends numerous tribes and genera both from the marine and fresh waters, all 

 characterized by a body more or less elongated, in most cases protected by pectinated scales, 

 generally rough to the touch, occasionally, however, appearing rather smooth, owing to the 

 deciduous nature of their prickles or pectinations. 



Regarding the fins, we observe that the dorsal is always well developed, sometimes single, 

 at others subdivided into two distinct fins. The anterior portion, or anterior fin, just as the 

 occurrence may be, being spinous — that is, composed of osseous and rigid rays — resembling 

 more common bones than ordinary rays. The anal exhibits a variable number of spiny rays at 

 its anterior margin, and which, in a few instances, are entirely wanting. The caudal fin is 

 either truncated posteriorly or more or less emarginated. The veatrals are inserted posteriorly 

 to the base of the pectorals, aqd composed of an external stoutish spine, and five soft and 

 dichotomised rays. 



Generally speaking, the preopercle and opercle exhibit various spinous or serrated edges, 

 while in a few only they are perfectly smooth and entire. The jaws, the front of the vomer, 

 and often the palatine bones also, are furnished with teeth of various kinds : velvet-like, card- 

 like, or of the canine type ; the canines occurring occasionally intermingled with the former 

 two kinds. 



The yellow perch, so common in the fresh waters of the eastern States, has not been brought 

 to notice beyond the main bed of the Mississippi basin, and hence was not met with by any of 

 the parties whose collections we investigate in the present report. 



Most of the percoids are fishes which appear upon our tables, some as delicacies, others as 

 ordinary staples. The less esteemed are the sunfish or pond perch, owing, mayhap, somewhat 

 to their diminutive size. 



