FISHES OF CHESAPEAKE BAY 145 
maturity is attained when the fish is much smaller. The exact size at which the sexual organs begin 
to develop has not been determined, but fish 1J4 inches long are plainly adult fish. 
This minnow is not generally common. It was taken at only five localities in Chesapeake Bay, 
and it was only fairly common in one of these places, namely, Love Point, Md. It frequents very 
shallow, brackish water, and is taken in company with F. heteroclitus. This species has rarely 
appeared in collections. It was first taken and described by Baird (1855, p. 334) from Beasely 
Point, N. J. Then it appears not to have been taken again until Smith (1892, p. 68) secured two 
specimens from the lower Potomac. Fowler records the species from Pecks Bay, N. J. (1912, p. 36), 
and from Cedar and Parramores Islands, Lotusville Branch, and Virginia Beach, Va. (1912, p. 57). 
The senior author found the species common in restricted areas near Beaufort, N. C. (1916, p. 306), 
and Crawford took some specimens at Lewisetta, Va. (1920, p. 75). The color of the female appears 
not to have been described previously. 
The species reaches a small size. The largest specimen taken in Chesapeake Bay during the 
present investigation was a female measuring 40 millimeters (lj% inches) in length. This fish, 
because of its small size and general scarcity, is of little or no commercial importance, either directly 
or indirectly. 
Habitat . — Coastwise in brackish water from New Jersey to North Carolina. 
Chesapeake localities. — (a) Previously recorded: Only from the lower Potomac. ( b ) Speci- 
mens in collection: Love Point, Md., May 11 and 12, 1922; Annapolis, Md., September 9, 1921, 
and May 1 to 3, 1922; Solomons, Md., April 27, 1922; Crisfield, Md., November 21, 1921; brackish 
swamp opposite Lynnhaven Roads, Va., June 10 to 17, 1921. 
Family XXXII.— PCECILIID/E. The top minnows 
Body elongate; compressed posteriorly; head depressed; mouth terminal, or nearly so; teeth 
pointed; no lateral line; dorsal fin small, composed of soft rays only; caudal fin usually round, 
never forked; anal fin in the male modified, some of the rays produced, others short and more or 
less coalesced, the fin forming an intromittent organ. Species viviparous. 
47. Genus GAMBUSIA Poey. Top minnows 
Body moderately robust; head rather short, depressed; mouth moderate, the lower jaw pro- 
jecting; teeth all fixed, pointed, in bands in each jaw; scales rather large; fins small, the anal fin 
in the male modified, the third, fourth, and fifth rays much produced, forming an intromittent 
organ; color plain; intestinal canal short; species viviparous. 
64. Gambusia holbrooki Girard. Top minnow. 
Gambusia holbrooki Girard, Proc., Ac. Nat. Sci., Phila. 1859, p. 61; Palatka, Fla. 
Gambusia afflnis Smith, 1892, p. 69, PI. XX (female); Jordan and Evermann, 1896-1900, p. 680, PI. CXIII, figs. 299 and 299a; 
Evermann and Hildebrand, 1910, p. 160. 
Head 3.5 to 4.4; depth 3.5 to 4.7; D. 7 or 8; A. 9 to 11; scales 26 to 30. Bodyrather robust 
moderately compressed, usually deeper in the female than in the male; caudal peduncle strongly 
compressed, its depth 1.75 to 2.3 in head; head depressed; snout short and broad, it length 2.85 to 
4.65 in head; eye 2.5 to 3.5; interorbital 1.8 to 2.5; mouth slightly superior, the lower jaw projecting; 
premaxillaries protractile; teeth small, pointed, in a band in each jaw; scales moderate, 12 to 14 
oblique series between the upper angle of gill opening and origin of dorsal; dorsal fin small, placed 
behind origin of anal; caudal fin rounded; anal fin similar to dorsal in female, modified into an intro- 
mittent organ in the male, the third, fourth, and fifth rays being much produced, placed propor- 
tionately farther forward in adult males than in females; ventral fins small, inserted much nearer 
tip of snout than base of caudal; pectoral fins moderate, 1.1 to 1.4 in head. 
Color of male and female similar but with considerable variation according to the environment 
because of the development of color adaptation; usually olivaceous above, grayish on sides, and 
pale underneath; scales on upper parts with dusky punctulations, these often concentrated on the 
margins of certain scales, forming irregular dark dots; a dark vertebral streak present in front of 
dorsal; a dusky area usually present under the eye and at occiput; dorsal and caudal usually slightly 
greenish and with dark dots (in light colored specimens the dots are frequently wanting); other 
