J881.] 
I^lZAftm FROH SCVADOR. 
229 
Peters as Cercosaura {Pantodactylus) argulm. Althougli the 
number and nrraiigeiiteut of tlie jtrtJeanail scutes afifords a conspicu- 
ous aud importnul cluirticter in Llie family Cercosauridee^ and in many 
cases A relinble onr, fiulBciiig, t'ur inEitance^ to distinguish several 
species of J^eposoma from the origuml one of Spix, and from the new 
one recently described hy Prof. Peters, allnwance must be ma(!e for 
a certain amount of inrintion in this pjirticular, more especially as 
corresponding variations in olber characteristic portions of the scu- 
tcllMtioii are to be found in the Lizards of this and closely ailtetl 
Son t li- A rn e r ica u gr 0 u jm , 
I have already noticed that the internasal plate is sometimea 
entire and sometimes bisected in Neusticurmecpleopns, Cope» althongb 
tliis species was described by Prof. Cope as differing from N. hicari- 
nuiuSf L,, in having it entire (see 'Ann. N. II,' Oct. p- 295). 
1 found also in K. bicarmatus an irregular additional prefrontal 
|)laie associated with tlie cleft internasal. In the present series of 
»^pecime»is of Cercasaura (Panioflacft/lua) arffulus, tiie iniernasal 
iias a langitudtna! cleft in a line with the suture of the fr on to- nasals, 
and occaBionally the above- mentioned supernumerary plaie i^ pre- 
sent ill exactly the same position as in Ncusiicus biearimtlus. The 
front o-iiasals are in tiiat case reduced to smaller triangular and more 
lateral plates^ quite se, arated from each other, instead of being large 
and extensively in contact. These two forms of arrangement of the 
nasal shields are assomated with two distinct types of prscaual acu- 
t ill ill ion. One specimen with the additional prefrontal has four 
narrow marginal prEcanals; another wi[b the norinat nasal plate;} 
has only two large rounded marginal ]ira:anals, like Cercosaum oceL 
iata, while the others have the normal nasals and the four narrow 
marginal preeanals. 
As Prof. Peters had only a single specimen from Bogota, 
and those in the present collection from Ecuador show a range of 
variation within recognizable specific limits, I give the following 
supplementary description — 
3. CERCdSAUKA ( pAxNTODAcniLUb) ARGULU5, Pcters, Abb, Afc. 
Beri. 1863, p. 184, pi. i. fig. 3* 
Internasal broiul, single, or bisected in a Hue with the suture of 
the two good-sii^ed fronto-uasals when these are estensiveiy in con- 
tact; sometimes an intermediate small praefrontal Joining the frontal 
and the internasal. Frontal and fronto-parietals of the ordinary 
shape, interparietal large, flunked by two large parietals^ and fol- 
lowed by a small occipital enclosed between two gooil-sixed postoc- 
eipitat plates. Nasal raiher large, followed by a single hrgc IrennL 
Supralabials six, none particularly elongate ; intralabials five, the third 
very elongate. Two jiairs of large postmentals in contact, the third 
smaller, separated by the group of large and small intervening gular 
£«aleB. Two contiguous rows of larger plates to tlie chest, where a 
small collar is formed by a central and two lateral roimded plates. 
Some convex scales behind the occiput ; scales of the back not very 
uarrow, keeled, pointe^J, the keels being slightly produced; on the 
