The Amphibians and Reptiles of Sinaloa, Mexico - Smithsonian ...

AMPHIBIANS AND REPTILES OF SINALOA, MEXICO 43
University of Illinois, Museum of Natural History; Stanford University Natural
History Museum; Robert C. Stebbins, Museum of Vertebrate Zoology, University
of California, Berkeley; Charles F. Walker, University of Michigan, Museum
of Zoology; Ernest E. Williams, Museum of Comparative Zoology, Harvard
University; William H. Woo din and Merritt S. Keasey, Arizona-Sonora Desert
Museum, Tucson; Richard G. Zweifel, American Museum of Natural History.
The Museum of Natural History, the University of Kansas, and the Allan
Hancock Foundation, University of Southern California, provided laboratory
space, library facilities, equipment, and supplies during the study. Most of the
field work in Sinaloa was financed by the United States Army Medical Research
and Development Command, contract number DA^9-193-MD-2215, awarded
to J. Knox Jones, Jr., of the University of Kansas and by Sigma Xi Grant to the
second author. We are grateful to the Society of Sigma Xi for providing funds
to assist the final preparation of the report.
We extend our thanks to the courteous officials of the Mexican government
and especially to the hospitable people of Sinaloa, without whose help our
objectives would not have been realized.
For the use of photographs of vegetation we thank the University of Kansas,
Museum of Natural History (photographs by Percy L. Clifton), James R,
Dixon, and Richard B. Loomis.
In appreciation for the consideration and understanding which was always
given when needed and for many hours of assistance during the final preparation
of the manuscript, the first author thanks his wife, Marilyn.
DESCRIPTION OF THE AREA
Physiography
Sinaloa is a long, narrow state that is situated on the western
coast of Mexico between 22°30' and 27'W north latitude and between
106*25' and 109°30 / west longitude; northward from Mazatlan
the coastline lies in a direction of approximately 315° from
north. The state has an area of 58,092 square kilometers (Encyclo.
Brit., 1967, 20:558) and a total relief of 2779 meters. Sinaloa is
bounded by Sonora to the north, by Chihuahua and Durango to
the east, and by Nayarit to the south.
The Sierra Madre Occidental lies along the entire length (about
560 kilometers) of the state on the east. In the northern part of
the state the Sierra Madre Occidental is less rugged and slightly
lower than in the southern half. A narrow coastal plain, which
consists mainly of mature outwash slopes from the adjacent mountains
and broad alluvial valleys associated with the major rivers,
extends the entire length of the state. In general the lowlands are
uniform except near Culiacan, where six small mountains {less than
900 meters in elevation) are separated from the sierra by lowlands
less than 300 meters in elevation. Sinaloa has seven small moun-