154 FISHES OF NORTH CAROLINA. 



these are .37 inch long and are able to swim at once. The old fish, at least in 

 aquaria, often devour the young as soon as born. 



The top minnow feeds on mosquitoes and other insects, the larvae of mos- 

 quitoes being the principal food in some places at proper season. Because of its 

 mosquito-eating propensity, the species plays an important role, and its intro- 

 duction into malarious and yellow-fever regions is strongly advocated Vege- 

 table matter, in the form of diatoms, desmids, and filamentous algae, is also 

 eaten. 



Genus HETERANDRIA Agassiz. Top Minnows. 



Very small, viviparous fishes inhabiting swamps, ditches, and sluggish 

 streams of southern United States, Central America, and West Indies; similar to 

 Gambusia in form and habits. Mouth small, jaws weak, a single row of slender, 

 movable teeth in each jaw, lower jaw short; fins small; anal fin in advance of 

 dorsal, modified in the male as in Gambusia. One species is found in South 

 Atlantic States. (Heterandria, different male.) 



131. HETERANDRIA FORMOSA Agassiz. 

 Top Minnow. 



Heterandria formosa Agassiz, Ms., 1853; Girard, Proceedings Academy Natural Sciences, Philadelphia, 1859, 

 62; Charleston, S. C, Palatka, Fla. Jordan & Evermann, 1896, 687, pi. cxiv, fig. 302. 



Diagnosis. — Body short, slightly compressed, depth .25 total length; length of head con- 

 tained 3.5 to 3.6 times in total length; mouth terminal, lower jaw slightly projecting; eye .33 

 length of head and 1.5 times snout; scales in lateral series 24 to 28; dorsal fin with 7 rays, its 

 origin over middle of anal; anal rays 6 to 9; caudal long, .2 length of body. Color: brownish 

 green; a dark band from mouth to caudal, ending at base of latter in a black spot; 6 to 9 verti- 

 cal dark streaks; a black spot at base of dorsal and anal, {formosa, comely.) 



Fig. 60. Top Minnow. Heterandria formosa. 



This is one of the smallest of fishes, the female being only 1 inch long and the 

 male .75 inch. The ascribed range is from South Carolina to Florida in black- 

 water swamps and ditches, but it has recently been found in the vicinity of 

 Wilmington, N. C, by Mr. W. P. Seal, who has forwarded a number of specimens 

 to the National Museum. Mr. Seal states that the species abounds in cypress 

 ponds and tidal ditches in that region, in company with Umbra, Fundulus, 

 Gambusia, and other small fishes characteristic of the lowland waters. 



