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Show 208 DR. H. GADOW ON MEXICAN [June 6, shrubs at the edge of a forest, were quite green, but they soon changed to reddish yellow and ultimately assumed the normal reddish colour. Of the 5 species of Leptodactylus, 3 are too little known. L. microtis from " Guanajuato " would be the only instance of the occurrence of a Leptodactylus on the plateau instead of in the lowlands. Only two species have a wide distribution : L. albilabris of South Guerrero, Oaxaca, and of Vera Cruz, also Antillean ; L. caliginosus from Paraguay northwards, in Mexico in the Pacific Tierra Caliente as far as Mazatlan. E n g y s t o m a t id ^e , with an obviously South-American centre of dispersal; not Antillean. The small genus Engystoma reaches through Mexico into the South-eastern United States (E. ustum). R a n id ^e .-This family is essentially Palseo-tropical. Scarcely more than a dozen species, all belonging to Rana, occur in North America, only 6 in Moxico, and fewer still further south, in the north-western portion of South America. There, however, the Ranidae have found a new congenial home, which has stimulated them into the development of 5 new genera, with about one dozen species, all arboreal, besides Dendrobates. The Ranidte have not found their way into the Antilles. Of the six Mexican species, R. forreri is restricted to the district between Durango and Mazatlan; R. pustulosa to same district and Western Jalisco; R. omiltemana to Guerrero mountains: these three are peculiar to Mexico. R. halecina is the common river-frog of the country, both in the hot parts and on the plateau, extending from the United States through the whole of Mexico down to Costa Rica. R palmipes ranges from southern tropical Mexico to South America. Lastly, R. montezumce, the largest of all, is a lake-dweller, e. g. lakes of Jalisco, near Mexico City, Tehuantepec, extending south into Tabasco and Guatemala. Resume of the Distribution of Mexican Anura. We can easily distinguish between northern and southern immigrants. 1. Northern, decidedly of Nearctic origin. jScaphiopus, scarcely reaching the Isthmus of lehuantepec; and a few Rana, all water-frogs. Both genera are comparatively recent immigrants, non- Antillean, although Rana extends through and beyond Central America. 2. Southern, of obvious South-American origin.-a. With related, or identical, species in the Greater Antilles. Cysti-gnathidce, not reaching the United States. Uylidce and Bufovidte, each, especially the Kyi id*, with genera peculiar to Mexico' indicating ancient residence.-b. Non-Antillean, a few Engysto-matinee, scattered through Mexico. |
