ghout the months of field work beginning in 1955 I constantly have
been aided by the authorities and workers of the Comision Tepalcatepec,
a subdivision of the Secretaria de Caminos y Obras Publicas, and of the
private corporation, Ingenieros Civiles Asociados. Much of the field
work in Michoacan was made possible only through the co-operation of the
natives who supplied mules, acted as guides, and aided in the collection
of specimens. I have learned a great deal from these people. They will
never see this report. Their work as guides, muleteers, and collectors
greatly assisted me with the mountains of equipment that had to be piled
on the backs of scrawny mules for transportation to places where the
natives seldom trod. Their efforts in behalf of Don Guillermo never will
be forgotten; I extend an especially hearty _muchas gracias_ to
Benjamin, Ignacio, Jesus, Lorenzo, Mariano, and Remigio.

Much of the work on this report was done while I was associated with the
Museum of Zoology at the University of Michigan. I thank Norman E.
Hartweg and T. H. Hubbell for making available to me the facilities of
the museum and for their numerous courtesies that aided me so much.

My field work in Michoacan was supported by the Museum of Zoology at the
University of Michigan (1951), by the Horace H. Rackham School of
Graduate Studies of the University of Michigan (1955), by the Penrose
Fund of the American Philosophical Society (1956), by the Bache Fund of
the National Academy of Sciences (1958), and by the University of Kansas
Endowment Association (1960).

Permits for collecting specimens in Mexico were provided by the
Direccion General de Caza through the courtesy of Ing. Juan Lozano
Franco and Luis Macias Arellano.

Historical Account

Unlike many parts of southern Mexico and northern Central America,
Michoacan received no attention from the collecting expeditions of the
European museums in the last century. The earliest known herpetological
specimens from Michoacan were obtained by Louis John Xantus, who was
appointed U. S. Consul to Colima in 1859. In April, 1863, Xantus
collected at Volcan Jorullo in Michoacan; in April and May of the same
year he collected along the coast of Michoacan between the Rio Cachan
and the Rio Nexpa. His small collection of 19 extant specimens is in the
United States National Museum. Alfredo Duges, a resident of Guanajuato,
Mexico, made early contributions to the knowledge of the herpetofauna of