650 Pareioplite, or Mailed-cheek Fishes 
fat and is much valued as food. About San Francisco it is 
dry and tasteless. 
The Greenlings: Hexagrammide.—The curious family of 
greenlings, Hexagrammide, is confined to the two shores of the 
North Pacific. The species vary much in form, but agree in 
the unarmed cranium and in the presence of but a single nostril 
on each side, the posterior opening being reduced to a minute 
pore. The vertebree are numerous, the scales small, and the 
coloration often brilliant. The species are carnivorous and 
usually valued as food. They live in the kelp and about rocks 
in California and Japan and along the shores of Siberia and 
Fic. 547.—Atka-fish, Pleurogrammus monopterygius (Pallas). Atka Island. 
Alaska. The atka-fish (Pleurogrammus monopterygius) is one 
of the finest of food-fishes. This species reaches a length of 
eighteen inches. It is yellow in color, banded with black, and 
the flesh is white and tender, somewhat like that of the Lake 
whitefish (Coregonus clupeiformis), and is especially fine when 
salted. This fish is found about the Aleutian Islands, espe- 
cially the island of Atka, from which it takes its name. It is 
commercially known as Atka mackerel. 
In this genus there are numerous lateral lines, and the dorsal 
fin is continuous. In Hexagrammos, the principal genus of the 
family, the dorsal is divided into two fins, and there are about 
five lateral lines on each side. 
Hexagrammos decagrammus is common on the coast of Cali- 
fornia, where it is known by the incorrect name of rock-trout. 
It is a well-known food-fish, reaching a length of eighteen inches, 
