CROCODILIANS, LIZARDS, AND SNAKES. 455 



I'upil round; eyelid distiuct all round the eye; digits narrow at the base, 



the dilatation strong and discoid; the distal joint strongly curved, 



the claw retractile between the anterior lamella?; inner digit rudl- 



mental, with very small, frei^uently indistinct claw. Lygodactylus Gray. 



Pupil vertical; distal, ioint of digits short; thumb clawless. 



LeindodactyliiH Fitzinger. 

 AAA. The free distal Joint at the extremity of the digital expansion ; a single 

 series of infradigital hiniella'. 



1. The distal Joint long. 



Digits narrowing gradually toward the end, the narrower portion not 

 forming an angle with the dilated basal part; eyelid distinct all .1 round 

 the eye 2{aulti)i us Gray 



The slender distal portion of the digit forming an angle with the dilated 

 basal portion HopJodactylus Dumoril and iJibron. 



2. The distal joint very short. 



Digits more or less webbed, inner clawed Rhacodactylus Fitzinger. 



Digits half- webbed, inner clawless Luperosauriis Gray. 



Digits free or slightly webbed, inner clawless Gecko Gray. 



Digits entirely webbed, inner clawless Ftychozoon Kuhl. 



\Ul. 1 )igits entirely dilated, clawed, without compressed ungual phalanx, inferiorly 

 with a single series of lamellae. 



liody cov(!rcd with small imbricate scales HomophoUs Smith. 



Body covered with large imbricate scales Geckolepin Grandidier. 



Body covered above with large juxtaposed scales, largest and subsymmetrical 



on the head EuvydactyJus Sauvagc. 



Body covered above with granular scales; the ch^ws of the three inner digits 

 turned inward, those of the two outer turned outward. 



^luronyx Fitzinger. 



IX. Digits dilated, only the third and fourth clawed Tarentola Gray. 



X. Digits (the lingers at any rate) more or less dilated, clawless. 



Pupil vertical; tips of toes dilated, with simple transverse lamelhe inferiorly. 



Pachydactylns Gray. 



Pupil vertical; tips of toes rather narrowed, witli ouly two small lamelhe infe- 

 riorly Coloptts Peters. 



Digits dilated at the apex only, inferiorly, with transverse lamelhe furnished on 

 their hinder edge with line fringes Dactychilikion Thominot. 



Pupil circular; eyelid distinct all round the eye riielsuma Gray. 



XI. Digits dilated at the apex only, with very small sheathed claw, the sheath 



opening laterally. 



Digital expansion with transverse hunelhe inferiorly Ilhoptropns Peters. 



Digital expansion with a circular ]>late inferiorly Spharodactyhis Wagler. 



The two i;euci'a which belong to oiu- fauna may be very easily distin- 

 gnished by the Ibllowing characters: 



rhyUodaetylus. — Digits all terminated by triangular pallets or disks, 

 with a longitudinal median groove beneath; claws exposed. 



tSplia'roclacfi/hi.s. — Digits all terminated by circular disks, without 

 central groove, and enshea thing the daws. 



Both of these genera enter the Nearctic liealm at the borders only, 

 the PhyUodacti/lus on the southwest and the Si)h(vro(la('ti/li(s on the 

 southeast, the former from the Mexican district and the latter from the 

 West Indian district of the Neotropical llealm. 



