FISHES OF CHESAPEAKE BAY 
141 
description, are readily recognized by the difference in the markings, the males having dark cross- 
bars only and a prominent dark spot on the last rays of the dorsal fin, while the females have two 
or three longitudinal dark lines along the sides and no black spot on the dorsal fin. 
The food of this fish consists of small mollusks, small crustaceans, small fish, and insects and 
insect larvae. Many of the stomachs examined contained a considerable amount of sand and 
some vegetable d6bris. In the field it was noticed that this killifish fed greedily on pieces of meat, 
bread, and on shrimp eggs. 
Spawning occurs from April to September, one female probably producing several broods of 
eggs during a single season. The eggs are rather large and spherical, measuring about 2 millimeters 
(12 to 14 to an inch) in diameter. Those of one brood are of uniform size. The ovary is single, 
and the largest number of eggs of uniform size contained therein in specimens examined was 540. 
In general the large fish produce more eggs at one time than the smaller ones. Sexual maturity 
is attained by the female when it has reached a length of approximately 3 inches, and the male may 
be sexually mature when 2)^ inches long. The largest fish caught during the present investigation 
was a female 8 inches long, which represents the maximum size of the species. The females reach 
a somewhat larger size than the males, the difference in the average length between the sexes among 
the adult fish being about one-half inch. 
This fish is very common in the vicinity of Chesapeake Bay and is found in bays, coves, creeks, 
tide pools, and along the outer shores. It is most abundant in small protected bodies of water, 
preferring especially to hover near the entrances to such places. It travels in schools of a few 
individuals to several hundred or more. On an ebbing tide it may be found on shallow flats, where 
the water it but a few inches in depth; but on a flood tide it adheres to the very shore’s edge, where 
it often is cast on the beach by the waves, from which it easily returns to the water. If placed on 
the beach some distance from the water the fish has the ability to reach its habitat by a series of 
jumps. Experiments of this kind were made by the authors. Fish were placed at various distances 
(5 to 20 feet) from the water’s edge. In almost every instance they jumped unerringly toward the 
water, progressing from several inches to several feet at a time. A special article on this apparent 
“homing instinct” in this species, written by Prof. S. O. Mast, appears in the Journal of Animal 
Behavior, vol. 5, No. 5, September-October, 1915, pp. 341 to 350. 
This fish is of no commercial value, but because of its general distribution and great abundance 
in Chesapeake Bay it is of importance as food for other species. 
Habitat . — Massachusetts to Florida in coastwise protected waters, brackish ponds, creeks, 
mouths of rivers, tide pools, etc. 
Chesapeake localities. — (a) Previous records: Patapsco, Patuxent, and Potomac Rivers, Hamp- 
ton Creek, Cape Charles, and other localities. (6) Specimens in collection: From all parts of 
Chesapeake Bay, along the shores from Baltimore, Md., to Lynnhaven Roads, Va., taken almost 
daily during the entire period of shore collection from April until November, 1921. 
61. Fundulus ocellaris (Jordan and Gilbert). Killifish; Ocellated killifish. 
Fundulus ocellaris Jordan and Gilbert, Proc., U. S. Nat. Mus., 1882, p. 255; Pensacola, Fla. Jordan and Evermann, 1896- 
1900, p. 642, PI. CII, fig. 274. 
Head 3.1 to 3.6; depth 3.7 to 4.3; D. 10 or 11; A. 9 or 10; scales 34 to 36. Body rather 
slender, compressed; caudal peduncle strongly compressed, its depth 1.8 to 2.3 in head; head 
depressed; snout moderate, 3.7 to 5.5 in head; eye 3.6 to 4.6; interorbital 2.2 to 2.7; mouth slightly 
superior, largely transverse; premaxillaries protractile; teeth all small, in a villiform band in each jaw; 
scales moderate, 18 or 19 oblique rows between upper angle of gill opening and origin of dorsal; 
dorsal fin moderate, much higher in the male than in the female, inserted over or slightly in advance 
of the anal, about equidistant from tip of tail and anterior margin of eye; caudal fin convex, some- 
what more so than in F. heteroclitus; anal fin of about the same size as the dorsal, notably higher 
in the male than in the female; the oviduct ending at base of first anal ray; ventral fins rather 
small, inserted about equidistant from anterior margin of eye and base of caudal; pectoral fins 
moderate, 1.65 to 2 in head. 
Color of female in life, brownish olive above, pale or slightly greenish below; lower part of sides 
from eye to anal yellowish; head, back, and sides of body irregularly sprinkled with black dots; 
sides with about 13 blackish cross bars; dorsal and caudal dusky golden, the base of these fins with 
