D i p l o l æ m u s D a r w i n i i . Mihi.
Squamis capitis convexis ; caxidà, corpox'c cum capite lougiox'e.
Habitat, P o rt Desire, Patagonia.
D e sc r ip t io n .— H e a d sh o rt, almost eq u ilate rally trian g u lar, risin g obliquely from th e muzzle to th e
vertex, th e n flattened. N o strils large , ro u n d , ea ch plac ed in fro n t o f th e su pra -orbital crest,
a n d in a line betwe en it a n d th e ce n tre o f th e muzzle. T h e ears are small, oval, th e margin
simple, a n d th e mem b ran a tym p an i superficial. T h e n e c k is considerably co n tra cted ; it has a
lo n g itu d in a l fold on each side formed by th e confluence o f two others, one o f w hich arises from
beliind th e angle o f th e mouth, an d th e o th e r from above th e ear, which is, as i t were, enclosed
betwe en th em ; th ey coalesce a little b eh in d th e ear. T h e re is also a d is tin c t transverse fold
on th e th ro a t, v e ry similar to th a t in Leiosaurus BelUi. T h e body is m odera tely thick, somewhat
depressed, an d w ith o u t th e slighte st appe arance o f a lo n g itu d in a l crest, or any elevation
along th e median line. T h e ta il is somewhat lo n g e r th a n th e h e a d an d body, n e a rly ro u n d an d
tap e rin g almost evenly from its origin to th e apex. T h e fore legs are sh o rt a n d modera tely
robust, th e toes short, n e a rly equa l ; th e h in d e r legs modera tely long. T h e forme r w hen plac ed
aga inst th e sides, do n o t re ach th e thighs b y n e a rly a th ird o f th e distance b etwe en th e two
limbs ; th e la tte r wh e n d ire c ted forwards, ju s t re a c h th e axillæ. T h e cloacal cove ring is semi-
lu n ar, tu rg id , a n d th e m arg in qu ite simple.
Scales cove ring th e u p p e r surface o f th e h e a d n umerous, ro u n d e d , an d considerably elev
ate d ; those betwe en th e two supra -orbital semicircles are in a double series. T h e occipital
p la te is oval, ra ised from th e margin, hollowed immediately a ro u n d th e ce n tre which is again
ra ise d like a m in u te tubercle. Above th e labial scales, is a series o f equal, ro u n d e d , oblong
scales, an d betwe en these an d th e p rin cip a l suborbital is a single series o f smaller ones, Scales
o f th e whole o f th e u p p e r a n d la te ra l p a rts o f th e neck a n d body ex trem ely small, slightly
e levated, passing a t the sides in to a flatter an d more e x p a n d ed form. Those o f th e whole o f
th e u n d e r p a rts are q u ite flat an d imbricated. B en e a th th e an te rio r p a rts o f th e lower jaw, an d
b eh in d th e broad m en tal scales, are a series o f flat, hexagonal scales on each side, passing backwards
and outwards, th e fro n t p a ir large a n d oblong an d th e others diminishing by degrees.
T h e scales o f th e th ro a t are very small, those on th e fold larg e r an d a c u te ly rhomboidal. T h e
scales o f th e a n te rio r p a r t o f th e belly are also rhomboidal an d those o f th e p o sterio r p ortion
hex ag o n al o r n ea rly qu ad ra te . T h e tail is covered by scales disposed in whorls, those on th e
median line b en e a th b e in g la rg e r th an th e others. B en e a th each toe is a series o f transve rse
h exagonal imbricated scales.
T h e colours an d markings o f this species are very difficult to be described, on ac count o f
th e g re a t irre g u larity o f th e ir disposition. T h e g ro u n d colour o f th e h e a d is yellow, passing
in to g re y on th e back p art. T h e a n te rio r p a r t has several small spots o f a d a rk brown colour,
an d th e re is a large r one on each orbit, an o th e r betwe en th e eye a n d th e ear, an d others on th e
back p a r t o f th e h e a d e x te n d in g to th e neck. T h e middle o f th e back is re d d ish yellow, on