REPORT OF COMMISSIONERS OF IXLAXD FISHERIES. 41 



line below the soft dorsal fin and breaks up into spots posteriorly; 

 above and below these are numerous brownish spots arranged in 

 rows. 



The following synopsis of the most important of the characters 

 distinguishing these species may be useful: 



A. Bpecies with dorsal fins widely separated. 



I. SMALL SPECIES WITH NO CAUDAL KEEL. 



1. The Common Mackerel. 



No air bladder; groove connects dorsal 

 fins; sides of body silvery. 



2. The Chub Mackerel. 



Air bladder present; no groove con- 

 necting dorsal fins; sides of body 

 silvery with dark spots; small in 

 size. 



II. SMALL SPECIES WITH CAUDAL KEEL. 



3. The Frigate Mackerel. 



No scales on posterior region of the 

 body; corslet present; teeth on 

 jaws only; no air bladder. 



B. Species with dorsal fins not separated. 



III. SPECIES OF LARGE SIZE WITH CAUDAL KEEL. 



a. Species in which a icell-developed corslet is present. 



4. The Horse Mackerel. 



Body very large, stout, and thick; 

 cone-like teeth on jaws only; dark 

 blue and grayish, in color with 

 silvery spots; 14 spines in first 

 dorsal fin. 



