176 MALACOPTERYGII. 
Sub-order VIII. MALACOPTERYGII. 
This sub-order is represented in the fresh waters of Mexico and Central America by 
a few fishes, mostly marine types. These are soft-rayed fishes with elongate or ovate 
scaly body and naked head ; dorsal, anal, and caudal fins are present, the pectorals are 
placed low and the ventrals are abdominal. The naked head, the maxillary forming 
part of the border of the mouth, the normal position of the lateral line (when present), 
and the larger number of rays in the ventral fins distinguish them externally from the 
Haplomi of this region. From the Characinide they may usually be distinguished by 
the larger number of branchiostegal rays, 
Synopsis of the Families represented in the fresh waters of Mexico 
and Central America. 
I. An adipose dorsal fin . 
II. No adipose fin. 
A. No gular plate; teeth small or absent. 
No laterallme . . . ee ee ee eee ee ew ee we 8, CLUPEIDE. 
1. SALMONIDA. 
Lateral line well developed . 2. 2. 1. 2. 1 ee eee ee eee 8. CHANIDA. 
B. A gular plate between the rami of the lower jaw; bands of villiform teeth 
in the Jaws and on the palate and tongue . ....... +. +. +. 4 Enoprpa. 
Fam. 1. SALMONIDA, 
The Salmonide are principally a circumpolar family of marine origin which are 
establishing themselves in fresh water in the Palearctic and Nearctic Regions. One 
fresh-water genus occurs in Australia and New Zealand. There are about twenty 
genera, but the number of species which should be recognized is very uncertain. 
1. SALMO, Linn. 
Oncorhynchus (Suckley, 1861) and Salmo, Jord. & Everm. Bull. U.S. Nat. Mus. xlvii. 1896, 
pp- 474 and 488. 
Body elongate, more or less compressed, covered with small cycloid scales. Lateral line present. Head 
naked; mouth large; conical teeth in the jaws and on the palate. Dorsal fin short, in the middle of the 
length of the fish; an adipose fin; anal short or of moderate length; caudal forked or truncate. 
The species are very variable and difficult to define; they inhabit the rivers and 
lakes of North America, Europe, and Asia; many of the forms are migratory, living 
part of their life in the sea and ascending rivers to spawn. 
1. Salmo clarkii, Richards. 
Salmo mykiss, Jord. & Everm. Bull. U.S. Nat. Mus. xlvii. 1896, p. 487. 
Salmo clarki, Jord. & Everm. t. c. 1900, p. 2819. 
Salmo irideus, Meek, Publ. Columbian Mus., Zool. v. 1904, p. 96. 
che ae Cn rn Re eee 
