IOO THE AMERICAN NATURALIST. | [Vor. XXXIX. 
a very illuminating discussion of the faunal regions into which Mex- 
ico is divided. . 
The new genera are Cynodonichthys, allied to Fundulus, but with 
large canines, Paragambusia, and Thorichthys, the latter related to 
Cichlasoma. Dr. Meek recognizes four distinct fish faunas in Mexico. 
One of these in the northeast is composed largely of migrants from 
the north, as Carpiodes, Ictalurus, Lepisosteus. Another is made 
up of migrants from the south, as Rhamdia, Cichlasoma, etc. The 
third region includes the valley of the Rio Grande de Santiago, in- 
cluding the now isolated lakes about the city of Mexico. This in- 
cludes most of the characteristic Mexican types as Chirostoma, 
Goodea, Aztecula, Evarra, etc. Very many species in this region are 
viviparous. The genus Chirostoma stands out as almost the only 
case among fishes where numerous closely related species inhabit 
exactly the same waters. In the large lake of Chapala, there are 
eight closely allied representatives of this type, all taken in the same 
nets, and all alike known in the markets as the “Pescado blanco,” 
noted for its delicate flavor. ‘These species are Chirostoma chapale, 
grandocule, promelas, sphyrena, lucius, lerme, ocotlane, and estor. 
In several other lakes, other species occur in similar assemblages. 
But one species of Chirostoma is known outside the Lerma-Santiago 
fauna. In almost every other case among fishes, where two closely 
related species occur, they are not in the same waters, but in neigh- 
boring waters. This indicates that almost all species of fishes have 
originated through geographical isolation. Possibly the forms of 
Chirostoma may have come into existence as mutations or saltations. 
In no other case in ichthyology is this theory equally plausible. The 
fourth faunal basin of Mexico includes the large river Balsas, flowing 
southward, and containing but few kinds of fishes. The most notable 
is a very large cat-fish peculiar to this basin, constituting the genus 
Istlarius. 
In the Bulletin of the Illinois State Laboratory of Natural History 
(March, 1904), Mr. R. E. Richardson gives a monographic review of 
the sun-fishes (Lepomis and Eupomotis) found in Illinois. He places 
euryorus in the genus Lepomis, and recognizes two species (gibbosus 
and Zeros) under Eupomotis. Apomotis Mr. Richardson unites with 
Lepomis. 
Otaki and Fujita have published two more folios of their “ Fishes 
of Japan,” (Tokyo, 1904.) with Japanese text, and large colored plates 
well executed, but of a size inconvenient for binding. 
