THE SILVERSIDES OF THE GENUS MENIDIA. 268 
approach typical M. notata, agreeing perfectly in nearly all specimens north of Cape 
cod: * 
The differential characters heretofore considered specific were the more backward 
situation of the first dorsal, fewer scales in longitudinal and cross series, and the 
deeper body of VW. menidia. From the accompanying comparative tables it will be 
seen that the scales increase in number, the first dorsal moves forward, and the body 
becomes more slender in many specimens from the successive northward localities. 
In Chesapeake Bay the differential characters do not conform to the specific 
requirements; thus individuals with the backward position of the first dorsal have 
the slender bodies and more numerous scales of M. notata and vice versa. With 
specimens from Woods Hole agreeing perfectly with M. notata, mixed forms as well 
as perfect M. menidia are found, the majority being the M. notata form. 
The range of Menidia menidia, as given by Jordan & Evermann in Fishes of North 
and Middle America, is from Cape Hatteras to Florida. Curiously, the range of M. 

Menidia menidia notata (Mitchill). 
notata, in the same work, is given south to Cape May, leaving an intervening space 
of many miles—Cape May to Hatteras—seemingly unoccupied by either form, but 
which is inhabited by the intergrading or mixed forms of M. menidia and M. notata. 
The comparative tables appended represent localities covering the coast pretty 
fairly from St. Johns River, Florida, to Gloucester, Mass.; at least representative locali- 
ties are shown sufficiently indicating the intergradation of the two forms. The 
intergradation, howeyer, is not uniform. As has been said, and as may be seen from 
the tables, specimens haye been taken in the Chesapeake which conform respec- 
tively to the descriptions of M. menidia and M. notata; at the same time others do 
not agree with the description of either, or rather partake of the characters of both 
forms to such an extent that it is impossible to say to which form it belongs. Speci- 
mens have been found at Wood Hole, even, which are essentially the M. menidia 
form. This is hardly an ideal intergradation, rather such as might be expected from 
the interbreeding of two closely related species and the occurrence of stragglers of 
either of the two forms or their hybrid offspring north or south of the point of the 
intermingling. 
