vi Introduction 



The length of the body is from the point of the snout 

 to the base of the caudal fin, the fin itself not being in- 

 cluded. 



The depth of the body is from the highest point of the 

 dorsal line to the lowest point of the ventral line, usually 

 from the base of the first dorsal fin to the base of the 

 ventral fin. 



The expression "head 5" means that the length of the 

 head is contained five times in the length of the body; 

 the expression "depth 5" means that the depth of the 

 body is contained five times in its length ; "eye 5" means 

 that the diameter of the eye is contained five times in 

 the length of the head. 



In describing the fins the spiny rays are denoted by 

 Roman numerals, and the soft rays by Arabic numerals, 

 and the fins themselves by initials; thus "D 9" means 

 that the dorsal fin is single and composed of nine soft 

 rays; "D. IX, 10" means that the single dorsal fin has 

 nine spiny rays and ten soft rays; when separated by a 

 hyphen as " D. X-12," it means that there are two 

 dorsal fins, the first composed of ten spiny rays and the 

 second of twelve soft ones; "A. Ill, 11" means that the 

 anal fin has three spiny rays and eleven soft rays. 



The expression "scales 7-65-18" indicates that there 

 are seven rows of scales between the dorsal fin and the 

 lateral line, sixty-five scales along the lateral line, and 

 eighteen oblique or horizontal rows between the lateral 

 line and the ventral line. 



The number of rays in the fins and the number of 

 scales along the lateral line, as given, represents the 

 average number, and is subject to slight variation ; thus 

 in some localities the number of rays in a fin may be 



