210 DR. H. GADOW ON MEXICAN [June 6, 
C. sonoriense in Sonora. C’. integrum (a variety of C. scorpioides) 
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. leucostomum extends from New Orleans along the Atlantic side 
of Mexico through and beyond Central America. C. effeldti is 
known from the State of Vera Cruz, San Mateo del Mar, and 
Guatemala. 
TESTUDINIDH.—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 rutila I have 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. 
Chrysemys 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 C’. grayi=wmobra and C. incisa go further south. C. ornata, 
from Panama to Tehuantepec, has been found by Forrer also 
near Mazatlan, with C. pulcherrima. I do not know of a single 
locality for Chrysemys on the plateau, or to the east of it, except 
for C. mobiliensis, which goes from Texas into the lowland of 
Nuevo Leon. 
’ This scarcity of Water-Tortoises in Mexico is rather puzzling. 
On the plateau Cinosternwm alone is found, 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. Chrysemys shuns such waters, and neither it nor 
Cinosternum occurs in those rivers which carry much sand. 
Chelone viridis was laying during July and August on the 
coast of Guerrero and Oaxaca. 
résumé of the Distribution of Mexican Chelonia. 
The Cinosternide, taken with the closely-allied Dermatemydidee 
and Chelydride, 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 Testudinide, the only family which has, 
recently, sent a United States Chrysemys into the Antilles and a 
South American into the Windward Islands. The Testudinide, 
plentiful in North America, scarce in Central, and with still 
fewer species in South America, have clearly come from the 
