FISHES OF EL SALVADOR 
257 
the conditions for its development appeared to be ideal. Water birds, however, 
are extremely abundant on this lake and the fish probably are unable to protect 
themselves against these enemies. 
The size attained by this species varies greatly in the different waters. The 
largest fish seen, ranging upward to 120 millimeters in length, were taken in small 
ponds at El Angel. Many large individuals were also taken in Lakes Guija, 
Coatepeque, and liopango. In Lakes Chanmico and Zapotitan, on the other 
hand, the usual size is rather small, the fishes ranging upward to only 55 millimeters 
in length. In this species, as in most top minnows, the males are smaller than the 
females, and sexual maturity is reached at a smaller size. Males 35 millimeters 
long appear to be full}^ mature, while the smallest mature female, among a limited 
number examined, was 60 millimeters. The males, as usual among the fishes of 
this group, are greatly in the minority. A lot of 245 fish gathered up at random 
after a discharge of dynamite on Lake Chanmico contained 80 males. 
A comparatively small number of the fish collected appear to be gravid, 
indicating that the period (January and February) during which the collections 
were made was not the principal spawning season. Only a single stage of devel- 
opment of the egg or embryo was found in any one ovary, indicating that broods 
of young probably are not born in such rapid succession as in some of the other 
species of top minnows. The largest number of embryos found was 82, which 
were taken from the ovary of a fish 90 millimeters long. 
The intestinal canal is about one-third longer than the total length of the fish. 
The contents of the stomachs of 24 specimens examined consisted mainly of 
disorganized masses, containing a relatively large amount of sand and some 
plant fragments, fragments of insects, minute ova (probably insect eggs), and in 
a few instances small (luantities of Entomostraca. The species is used for 
mosquito control in Nicaragua by Sanitary Engineer F. E. Hulse, of the Inter- 
national Health Board, apparently with success, but it is believed from the field 
observations made, and from the examination of stomach contents, that its 
relatives, Priapiclithys letonai and P. fosteri, are more efficient agents for the 
control of the malaria-transmitting mosquitoes. Anopheles. 
This fish, as here understood, is a widely distributed, variable species, several 
nominal species having been defined. Much variation exists with respect to the 
depth of the body, shape of the dorsal and caudal fins, and especially with respect 
to color. These characters, however, appear to intergrade. Careful measure- 
ments and scale and fin counts were made of 40 specimens, selected to include all 
the extremes of variations. The minute structure of the intromittent organ, which 
is regarded as a very helpful character in determining species, was critically studied 
in all the extreme color phases represented among the El Salvador specimens, 
and this organ also was compared with others taken from specimens from Nicaragua 
and Panama and found to be identical. The range, as here understood, includes 
both slopes from southern Mexico to northern Colombia. This is one of a very 
few species of fishes that have previously been recorded from the fresh waters of 
El Salvador. Our specimens were collected in the following localities: Lake Guija, 
Rio del Desague, Lake Metapan, Lake Chalchuapa, Rio Pampe near Chalchuapa, 
Lake Ahuachapan, Lake Coatepeque, Lake Chanmica, Rio Sucio near Sitio del 
