ORDER. 
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, spiny 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 ventrals are inserted posteriorly 
to the base of the pectorals, and 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. 
