210 DR. H. GADOW ON MEXICAN [June 6, 



C sonoriense in Sonova. C. integrum (a variety of C. scojyioides) 

 is likewise Pacific, from Jalisco, e. g. Lake Chapala, to which I 

 can now add Zapotlan and the small rivers on the plateau south 

 of Oaxaca and the swamps of San Mateo near Tehuantepec. 

 C. levxostomuin extends from New Orleans along the Atlantic side 

 of Mexico through and beyond Central America. C. effeldti is 

 known from the State of Vei'a Cruz, San Mateo del Mar, and 

 Guatemala. 



Testudinid^. — Cistudo with two species in North America and 

 one in Yucatan, strictly terrestrial. C. mexicana of Texas and 

 New Mexico, e. g. San Marcial. How far it extends into Mexico 

 is not known ; Tampico is quite possible, but I very much doubt 

 *' Mexico City " and neighbourhood. 



Nicoria rittila I haA^e met in swampy bush-land of the State of 

 Vera Cruz and near Tehuantepec, and this seems to be its range ; 

 allied species occur in Central America. 



fJlm^ysemys extends from Canada to Argentina, but with a 

 preponderance of northern forms. In Mexico restricted to the 

 hot countries, and even there common only about the Isthmus, 

 whence G. grayi=^imnhra and C incisa go further south. C. ornata, 

 from Panama to Tehuantepec, has been found by Forrer also 

 near Mazatlan, with C. 'pulcherrmia. I do not know of a single 

 locality for Cliryseinys on the plateau, or to the east of it, except 

 for C. 7nobiliensis, which goes from Texas into the lowland of 

 Nuevo Leon. 



This scarcity of Water-Tortoises in Mexico is rather puzzling. 

 On the plateau Cinosternum alone is foimd, and these thick-shelled 

 box-like creatures are, moreover, the only kind which can with- 

 stand the buffeting to which they are subjected in the torrents 

 into which the rivers of the slopes of the plateau are converted in 

 the rainy season. The Tortoises hide then under the boulders in 

 the stream. C'hrysemys shuns such waters, and neither it nor 

 Cinosternuini occurs in those rivers which carry much sand. 



Chelone viridis was laying duiing July and August on the 

 coast of Guerrero and Oaxaca, 



Resume of the Distribution of Mexican Chelonia. 



The Cinosternidse, taken with the closely-allied Dermatemydidte 

 and Chelydridfe, are autochthonous Americans ; the first a 

 Sonoran, the second obviously a southern group so far as the present 

 distribution is concerned. Both Chelydrids and Dermatemyds 

 are known from the Cretaceous of North America. The three 

 together may well be regarded as originally northern and ancient. 

 The same applies to the Testudinidee, the only family which has, 

 recently, sent a United States Chrysemys into the Antilles and a 

 South American into the Windward Islands. The Testudinidee, 

 plentiful in North America, scarce in Central, and with still 

 fewer species in South America, have clearly come from the 



