Percesoces and Rhegnopteri 433 
known as “‘fishes of the King,’’ Pescados del Rey, Pesce Rey, or 
Peixe Re, wherever the Spanish or Portuguese languages are 
spoken. The species are, in general, small and slender fishes 
of dry and delicate flesh, feeding on small animals. The mouth 
is small, with feeble teeth. There is no lateral line, the color 
is translucent green, with usually a broad lateral band of silver. 
Sometimes this is wanting, and sometimes it is replaced by 
burnished black. Some of the species live in lakes or rivers, 
others in bays or arms of the sea, but never at a distance from 
the shore or in water of more than a few feet in depth. The 
larger species are much valued as food, the smaller ones, equally 
delicate, are fried in numbers as ‘‘ whitebait,’’ but the bones are 
firmer and more troublesome than in the smelts and young 
herring. The species of the genus Atherina, known as “friars,” 
or “brit,” are chiefly European, although some occur in almost 
all warm or temperate seas. These are small fishes, with the 
mouth relatively large and oblique and the scales rather large 
and firm. Atherina hepsetus and A. presbyter are common in 
Europe, Atherina stipes in the West Indies, Atherina bleekert 
in Japan, and Atherina insularum and A. lacunosa in Polynesia. 
The genus Chirostoma contains larger species, with project- 
ing lower jaw, abounding in the lakes of Mexico. Chirro- 
stoma humboldtianum is very abundant about Mexico City. 
Like all the other species of this genus it is remarkably excellent 
as food, the different species constituting the famous ‘‘ Pescados 
Blancos” of the great lakes of Chapala and Patzcuaro of the 
western slope of Mexico. A very unusual circumstance is this: 
that numerous very closely related species occupy the same 
waters and are taken in the same nets. In zoology, generally, 
it is an almost universal rule that very closely related species 
occupy different geographical areas, their separation being 
due to barriers which prevent interbreeding. But in the lake 
of Chapala, near Guadalajara, Prof. John O. Snyder and the 
present writer, and subsequently Dr. S. E. Meek, found ten 
distinct species of Chirostoma, all living together, taken in the 
same nets and scarcely distinguishable except on careful 
examination. Most of these species are very abundant through- 
out the lake, and all reach a length of twelve to fifteen inches. 
These species are Chirostoma estor, Ch. lucius, Ch. sphyrena, 
