Var. C. L e dessus d u corps est uniformément p e in t d’u n v ert olive. L e dessus du cou, le
milieu de la p o itrin e e t celui d u v en tre sont d’u n n o ir profond.
DIMENSIONS.
Inches. Lines.
Length of the head.................................. 0 7
of the body 2 8
of the tail .................................. 4 2
T o ta lle n g th .... 7 7
Length of anterior ex trem ity ................ 1 2
of posterior extremity ............ 2 0
This species agrees with P r . Darivixiii and Weigmannii, and in some degree
with P r . Kingii, in having a portion of the posterior face of the thighs covered
with imbricated scales. This is a character, which although existing in all those
which I have named, is found to obtain in very different degrees; in T r . Weig-
mannii being very distinctly marked, and in T r . K in g ii very slightly so, and in
some specimens scarcely notable. I t is probable, th a t var. B., and possibly A.
also, of Mons. Bibron, may be P r . K in g ii ; but I have not had the opportunity of
ascertaining this from the actual examination of the specimens.
Found by Mr. Darwin at Port Desire, and at Santa Cruz, in Patagonia.
P r o c t o t r e t u s c y a n o g a s t e r .
P late V.—F ig . 2.
Squamis capitis neque imbricatis nec carinatis ; temporum imbricatis, subcarinatis,
margine rotundato ; aurium margine anteriore simplici ; squamis dorsalibus rhombeis,
laxis, cariné posticè acuta ; femorum facie posteriore omninò granulosâ ;
corpore suprà oliváceo, fascia utrinque longitudinaliflavescenti ; abdomine cceruleo.
Proctotretus cyanogaster, Bibr. 1. c. p. 273.
Habitat, Valparaiso, and Valdivia, Chile.
D e sc r ip t io n .— I t has been well observed by M. B ibron th a t this species offers a t first sig h t somewh
a t the g en e ral aspect o f th e g en u s A lg ira ; th e acute p o in ts o f th e dorsal an d lateral scales
a n d the gene ral form giving very ranch th a t appearance.
T h e h e a d is o f moderate size, somewhat deflexed ; th e scales moderate, flat an d smooth ;
those o f th e temples are slightly carinated, imbricated an d ro u n d e d : those o f th e sides o f the
neck small, n o t g ranula r, b u t rhomboidal an d imbricated. T h e r e is b u t a single series o f oblong
scales betwe en th e labial ones an d th e orbit. T h e m arg in o f th e e a r is en tire and simple ; th e