of the Geckos. I ts habits are singular. I t lives on th e dry sand of the beach,
at some distance from the vegetation, and the colour of the body much resembles
th a t of the sand. When frightened it depresses its body, stretches out its
legs and closing its eyes tries to escape detection. I f pursued it buries itself
with great quickness in the sand ; but as its legs are short, it cannot run very
swiftly.”
P r o c t o t r e t u s p e c t i n a t u s .
P late IX .—F ig . 2.
Capite squamis subcequalihus, rhomboideis, imbricatis, carinatis tecto.
Proctotretus pectinatus, Bibr. Hist. Eept. V\ . p. 292.
Habitat, Patagonia.
D e sc r ip t io n - T h e scales o f th e h e a d are n arrow, closely imbricated, stro n g ly b u t n o t acutely
carinated, a n d th e a n te rio r ones arran g e d in somewhat o f a ra d ia tin g d irec tio n from th e muzzle.
T h e re is b u t a single series o f scales betwe en those o f th e u p p e r lip an d th e orbit, a n d these,
to g e th e r w ith all th e scales ab o n t th e h ead , p a rta k e o f th e ca rin a ted a n d e longa ted ch a ra c te r
already described. A single s trong trian g u la r scale an d two smaller ones are p lac ed on th e
a n te rio r margin o f th e ea r, which is n arrow, oval and reniform. T h e scales o f th e temples and
sides o f th e neck are rhomboidal, acute, c a rin ated an d imbricated. T h e r e is a lo n g itu d in a l
fold on each side o f th e n e c k an d a transverse one a n te rio r to th e shoulder, b eh in d which is a
deep depression. T h e scales o f th e back an d side are p rom in en tly a n d acutely c a rin ated , those
o f th e ce n tra l lin e bein g ra th e r more p rom in en t th a n th e o th e rs ; an d above th is th e re is on
e ach side a marked lo n g itu d in a l la te ra l crest ex te n d in g from b en e a th th e eyes to th e base ot
th e tail. T h e scales co n stitu tin g theso crests are very p rom in en t, narrow an d acutely carinated.
T h e scales o f th e belly are also imbricated an d rhomboidal, b u t fiat; those o f th e u n d e r surface
o f th e h an d s an d fe et are c a rin a te d ; a n d those o f the toes have th re e carinæ. T h e bod y is
somewhat depressed as is th e tail a t its commencement, becoming more ro u n d e d an d ra th e r
ab ru p tly smaller a t some distance from its origin. T h e fore-foot reaches to ab o u t two-lhirds o f
th e distance from th e shoulder to th e side, an d th e h in d e r ex trem ity th u s plac ed extends to th e
shoulder. , « rei,.
T h e colours o f th is most e le g an t o f all th e species o f th e g en u s are v e ry b eau titu l. I h i s
is th e most bea u tifu l lizard,” says M r. D a rwiu , “ I have ever s e e n ; th e back has th re e rows of
re v n la r oblong marks o f a ric h brown, th e o th e r scales symme trica lly coloured e ith e r ash or
liAht b row n ; m a n , o f th em o f a b rig h t eme rald g re e n ; b e n e a th p ea rly , with semlhmar spots o f
b rillia n t orange on th e th ro a t.” I find in th e specimens I have ex am mc d th a t th e p e c tin a ted
late ra l crests are white, an d th e brow n oblong marks o f th e back are b o rd e red wilh a similar
colour. T h e re are always th re e white transverse lines across th e head.
EE P T IL E S . >9
DIMENSIONS.
Inches. Lines.
Length of the head .............................. ^ 7
of the b o d y .............................. ^
of the tail ............................... ^
T otallength 5 5
Length of anterior extremity ............ 1 0
of posterior- extremity............ t 5
This species, as has been observed by M. Bibron, who Aist described it
may be at once distinguished from every other by the character of
the head, which, instead o f l y i n g flat, with the edges m contact
imbricated and carinated. Another obvious distinguishing charac er. is the
narrow line of prominent scales running the whole lengffi of the ™ ^
side, forming a sort of pectinuted lateral crest, from which circumstance
p L ’n d T y Mr. Darwin, a t Bahia Blanca, and P o rt Desire in Patagonia.
G e n u s -D IP L O L ^M U S . S e l l
Caput breve, Utum, subtriangulare. Anres parvce, ovata,
la g n a , rotunda. Collum infrà transversè, ad latera longUud.nahter pheai^m.
Corpus suidepressum, non cristatum. Cauda teres, brevmscula, lams P e d ^
breves, robusti. Squamai capitis numerosa, parva, rotundata non
corporis UÌÌN6 caudee suprà minima, laves, " f “
plana. Pori femorales et prm-anales in utroque scan nulh. Dentes palatini
nulli.
The new genus which I have thus defined, resembles very closely, in most of its
characters the genus Leiosaurus of B ibron ; from which, indeed, it scarcely differs,
c r p t i n g in the absence of palatine teeth, and in the form of the snborhitar
plates, wliich in Leiosaurus are all distinct, and of n early equal size i «Pereas n
the nresent genus, three of these are united to form one plate, resembling that
P ™ * and some other Agamida. In other respects the genera are very
closely allied • b u t the existence or non-existence of palatine teeth is a character
o f s o m u ^
by M. Bibron. who examined the specimens with m e .- th a t they should be considered
as distinct. Both the genera are natives of South America Of icmx
rus SeUii (Bibr.) the only known specimens were presented to me by Capt. Km ,
who obtained them during his survey, from whom also I obtained specimens
one of the species of the present genus, D . Bihronti.