s
of about equal size (and collected at the same time) there is
considerable variation in the amount of blue on the belly. In a few of
the males the belly is white with only the anterior edge of each scale
blue; in some only the lateral rows of ventrals on the posterior
two-thirds of the body are blue; in others all of the posterior
two-thirds of the belly is blue.

_Ontogenetic Change in Color Pattern._--The metamorphosis of color
pattern in _Cnemidophorus sacki zweifeli_ results in the dorsal
ground-color becoming paler with age, the replacement of the stripes
by spots, and finally in large males the suffusion of these spots.

A single hatchling (UMMZ 114732) is available; this specimen has a
prominent umbilical scar and a snout-vent length of 34 mm. The top of
the head is olive brown; the dorsal surfaces of the limbs are dark
brown with cream mottling; the dorsal ground-color is brownish black;
this is paler on the lower flanks. The lateral and dorsolateral
stripes are cream-colored; the paravertebral stripes are white. There
is a faint, diffuse vertebral stripe anteriorly (Fig. 2 A). The throat
and undersides of the limbs and tail are cream-colored; the belly is
bluish white. In life the stripes were pale yellowish green, and the
tip of the tail was pink.

In larger individuals the dorsal ground-color is dark brown; the
lower flanks are grayish tan. Light brown diffuse spots are present
in the lateral and dorsolateral dark fields. The tan vertebral stripe
is diffuse and nearly fills the paravertebral dark fields; the
paravertebral stripes are faint posteriorly; throughout their length
they are scalloped--the beginning of their fragmentation into spots
(Fig. 2 B).

In subadults (+- 80 mm. snout-vent length) the paravertebral stripes
are fragmented into spots posteriorly. Also, the dorsolateral stripes
in some individuals are fragmented posteriorly. The dorsolateral dark
fields are somewhat paler than the lateral dark fields. Cream-colored
spots are present on the flanks. The mottling on the thighs tends
towards the formation of light spots (Fig. 2 C).

In small adults (+- 100 mm. snout-vent length) the paravertebral
stripes are entirely fragmented into spots. The lateral and
dorsolateral stripes are broken into spots posteriorly. The middorsal
pale area (formed by the suffusion of the vertebral stripe) and
paravertebral and dorsolateral rows of spots are pale green. The
cream-colored spots on the flanks are ex