PISCES. 213 | 
cycloid structure. These have recently been placed by Prof. Agassiz in a 
new family, Percopsida.* _ 
Gataxia. This family, containing but few forms, exhibits characters 
intermediate between the Salmonoids and the Esocide. With a structure 
somewhat similar to some of the former, it has the dorsal far back, and the 
intestinal character of the latter. The upper jaw is formed partly by a 
short intermaxillary, partly by the maxillary. The mouth presents much of 
the cyprinoid structure. The species are mostly oriental. 
Esocwa. In the Hsocide the body is elongated, the single dorsal placed 
far back, and opposite the anal. The upper jaw is constituted by the inter- 
maxillaries, almost entirely ; the maxillaries when they enter as an element 
are destitute of teeth. Intestines without ceca. Teeth generally well 
developed in various parts of the large mouth. Branchiostegous rays from 
three to eighteen. 
The genus Hsow is characterized by the broad depressed head and mouth ; 
the latter with teeth on the tongue, vomer, palatines, and branchial arches. 
The jaws have long, sharp, compressed teeth. The Hsoces, or pikes, are 
among the most formidable of all fresh-water fish. By reason of their 
slender elongated form, they are able to live in shallow waters; penetrating, 
even when of considerable size, into very small brooks. Tyrants of the 
fresh water, no fish can compete with them except the trout; and it is very 
seldom that both forms are found in the same waters. Of two branches of 
the same stream, one may be peopled by the former, and the other by the 
latter. The only species of pike found in Europe is the Esoxr luctus, 
shown in pl. 82, fig. 3. It is found in all the principal fresh waters of 
Europe ; where, there is reason to suppose, they are much more abundant 
at the present time than formerly. This species attains to a weight of 
70lbs., although individuals of this size are of rare occurrence. North 
America is especially rich in species of pike: those inhabiting the northern 
lakes, as the Maskalonge, Esox nobilior, Ksox estor, and others, attain a 
great size. Specimens of the former have been known of over 70lbs. The 
more southern species, as Hsox clathratus, and others, are of more moderate 
dimensions. The American species may all be referred to two types, one 
with the opercula entirely scaled, and with fasciated or reticulated darker 
markings, with a vertical bar under the eye; the other with the lower half 
of the operculum free from scales, and the marks in the form of light spots 
on a dark ground. | 
Mormyrwa. This family contains fish characterized by an elongated 
body provided with oblong scales. The entire head, not excepting the 
cheeks and operculum, covered by a thick skin completely concealing the 
bones of the head. This is drawn over the operculum, in such a manner 
as only to leave a vertical narrow slit in each side: this skin is perforated by 
a number of pores. Mouth, with the tongue, well armed with teeth. Two 
cecal appendages. The fishes of this family are almost all inhabitants of Africa. 
* Since the above paragraph was written it has been ascertained by Prof. Agassiz that the 
genus Percopsis, with Corniger (from Brazil) must constitute a distinct order of fishes. It 
is likewise possible that the three species referred to are really one. 
ICONOGRAPHIC ENCYCLOPDIA.—VOL, II. 27 417 
