Lake Otero, N. Mex.—Herrick. 185 
apparatus controlling- the chromatophc-es or the bleaching of 
the colors themselves. In the case of the lizard, Holbrookia 
tcxana, which is a rather poor pedestrian, the transformation 
of the upper parts is nearly complete but the characteristic 
blue bands remain below in contrast to the original white of 
the under parts. Crotophytiis colaris, a very fleet and active 
species which can, upon occasion, pick up its tail and fore feet 
and make great progress as a biped, like some of its gigantic 
forebears in the west, is little if any modified so far as ob- 
served. 
Extent of Lake Otero. — So far as we can now determine, 
the area of this ancient lake may have been from 1600 to 1800 
square miles. We have made no examination to the south 
to ascertain if the nature of the barrier can be made out. It 
may have extended nearly to the Jarillas mountains. From 
the nature of the case, the old shore lines must be deeply 
buried under the talus from the mountains whose fans spread 
out a great mantle of lime debris. Near Alamogordo at 
the mouth of one of these mountain canons a well was drilled 
over 800 feet without reaching- solid rock. Along the gradual 
slope west of the southern tongue of mal pais, i. e. along 
what was the northwest border of the lake, erosion has ex- 
posed what seem to be remnants of old lake benches. At no 
other place have they been observed though three or four 
distinct benches border the playas upon the Tularosa forma- 
tion. 
We may assume that the saline lake began in Tertiary 
time and continued with minor changes to a period of disturb- 
ance which may have coincided with the lava flow already 
mentioned. If the extrusion of so vast an amount of lava 
caused a sinking of the northern part of the valley, a deepen- 
ing of the lake would result and a corresponding diminution 
in extent which might account for a greater depth of water 
and a corresponding freshening of it. The extent to which 
the sheet has been undennined by subterranean erosion indi- 
cates a considerable antiquity. It is moreover possible that 
the Otero beds do not really underlie the lava, as they appear 
to do, in which event our only clue to the age of these beds 
is inapplicable. 
