REPORT OF COMMISSIONERS OF INLAND FISHERIES. 39 



Seven species of the ^Mackerel family are found in Rhode Island 

 waters. According to the peculiarities of their structure they may 

 be divided into the following three groups: 



I. SMALL SPECIES WITH NO MEDIAN KEEL at the root of 

 the tail fin. The two back fins are widely separated; the body is 

 covered with very small scales, and there is no sign of a corslet; the 

 mouth is large; there is a single row of very small, slender teeth on 

 each jaw and on the roof of the mouth. In this group there are 

 two species: 



1. The Cominon Mackerel. Scomber scomhrus. Plate III. 



This has no air bladder; there are 11 or 12 spines in the first dorsal 

 fin; a groove connects the two dorsal fins; the body is dark blue 

 above, with about 35 wavy, blackish, transverse streaks; the under 

 sides of the body below the middle line are silvery and irridescent. 



2. The Chub Mackerel. Scomber colias. Plate IV. 



The air bladder is present; the eye is somewhat larger than in 

 the Common Mackerel; 9 or 10 spines in the first dorsal fin; no 

 groove connecting the two fins; its color is blue with about 30 wavy, 

 blackish streaks across the back; these are less definite than in the 

 Common ^lackerel; below the middle line the sides are silvery, but 

 in the adult they always have roundish, dusky spots or cloudings; 

 in size it is smaller than the Common Mackerel. 



II. SMALL SPECIES WITH A MEDIAN KEEL at the root of 

 the tail. Dorsal fins well separated; the posterior region of the 

 body has no scales except along the lateral line; the forward part is 

 covered with small scales of which those in the breast region are 

 enlarged and form a corslet; mouth rather small; teeth very small 

 and on the jaws only; the air bladder is not present. In this 

 group there is only one species: 



