ales is corroborated by
personal observations in the Tepalcatepec Valley in April and May. In
the summer rainy season the lizards are active in the morning and
again in the late afternoon; only _Cnemidophorus calidipes_ is active
during the heat of the midday. In some areas of the scrub forest
_Cnemidophorus sacki zweifeli_ is found in association with
_Cnemidophorus communis communis_. Throughout the scrub forest _C.
sacki zweifeli_ occurs with _C. deppei infernalis_. In some of the
more dense scrub forest, where _C. sacki zweifeli_ is not so abundant
as in the more open forest, it has been taken with _C. lineatissimus
exoristus_. In the open _Acacia-Cercidium_ associations on the valley
floor _C. sacki zweifeli_ occurs with _C. calidipes_.

This subspecies is not restricted to the scrub forest. On the lower
slopes of the Cordillera Volcanica in Michoacan _C. sacki zweifeli_
has been collected in open pine-oak forest near Zirimicuaro and
Ziracuaretiro.

_Distribution._--_Cnemidophorus sacki zweifeli_ inhabits the valley
of the Rio Tepalcatepec in Michoacan and probably extreme southwestern
Jalisco, and the western part of the Balsas Basin in Michoacan. No
specimens have been seen from extreme western Guerrero, but _C. s.
zweifeli_ may occur there.

_Specimens examined._--Catalogue numbers are preceded by abbreviations
of the name of the institution as listed in the acknowledgements.

_Cnemidophorus sacki occidentalis_, 22 specimens, as follows:
_Jalisco_: 8 km. E of Ameca, UMMZ 102045; 7 km. SE of Ameca, UMMZ
102046; Autlan, UMMZ 102044, 102219-21; 7 km. ESE of El Arenal, UMMZ
114736 (2); San Gabriel, UMMZ 102040, 102042-3. _Michoacan_: 2 km. ESE
of Jiquilpan, UMMZ 117557 (3). _Nayarit_: Ixtlan del Rio, UMMZ 104747;
San Jose de la Conde, UMMZ 102047 (4); 5 km. N of Santa Isabel, UMMZ
102048-50.

_Cnemidophorus sacki sacki_, 108 specimens, as follows: _Guerrero_:
Chilpancingo, UMMZ 72426 (8), 73937 (7), 88422 (4); 8 km. W of
Chilpancingo, UMMZ 119144 (4); 5 km. N of Iguala, UMMZ 114712 (11);
15 km. N of Iguala, UMMZ 99039; Mexcala, UMMZ 114711 (10); 8 km. S of
Taxco, UMMZ 114709 (2). _Morelos_: Amacuzac, UMMZ 114716; 3 km. S of
Cuautla, UMMZ 99031 (9), 99917 (11): Rio Cuautla, UMMZ 99038 (6); 5 km.
S of Temixco, UMMZ 114718 (12); _Puebla_: 5 km. SE of Izucar de
Matamoros, UMMZ 112650 (4); 13 km. SE of Izucar de Matamoros, UMMZ
117497 (2); 3 km. NW of Tehuitzingo, UMMZ 114714 (10); 1 km. N of
Teyuca, UMMZ 114713 (