38 LACERTILIA. 
9. Gerrhonotus rudicollis. 
Gerrhonotus rudicollis, Wiegm. Isis, 1828, p. 379; and Herpet. Mex. p. 31, t. 10. fig. 1; Bocourt, 
Miss. Sc. Mex., Rept. p. 367, t. 21 3. figg. 3. 
Barissia rudicollis, Gray, Cat. Liz. p. 55. 
Hab. Mexico (Deppe). 
Dorsal scales strongly keeled and, like the ventral, in twelve or fourteen, nuchal in 
four or six longitudinal series. Nasal in contact with the rostral; supranasals none. 
Three pairs of shields on the upper surface of the snout, between vertical and rostral. 
Sides with brown irregular cross bands. 
One specimen only is known. 
10. Gerrhonotus imbricatus. 
Gerrhonotus imbricatus, Wiegm. Isis, 1828, p. 379; and Herpet. Mex. p. 34, t. 10. fige. 2&5; 
Dum. & Bibr. Erp. Gén. v. p. 407; Bocourt, Miss. Sc. Mex., Rept. p. 363, t. 21. figg. 2. 
Gerrhonotus lichenigerus, Wagl. Ic. Amph. t. 84. fig. 2; Wiegm. Herpet. Mex. p. 35, t. 10. fig. 6 
(G. adspersus) ; Bocourt, 1. c. p. 865, t. 21 B. figg. 1 (G. imbricata, var.). 
Barissia imbricata, Gray, Cat. Liz. p. 55. 
Hab. Mexico, Cuernavaca and Guanajuato (Bocourt), City of Mexico (Brit. Mus.), 
Vera Cruz (Boucard), Tehuantepec (Swmichrast). 
Dorsal scales keeled, in twelve or fourteen longitudinal series. The nasal is not in 
contact with the rostral; supranasals none. ‘Three pairs of shields on the upper 
surface of the snout, all very convex. 
This well-known species is subject to variation of colour, white dots being irregularly 
scattered about the scutes of the head and body. The mental scute is generally 
followed by a pair of scutes, more rarely by a single one. 
11. Gerrhonotus planifrons. 
Gerrhonotus planifrons, Bocourt, 1. c. p. 861, t. 21 c. figg. L. 
Hab. Mexico, Oaxaca (Boucard). 
This form, if it should prove to be a constant modification, differs from the typical 
G. imbricatus in having the head-shields flat, and sixteen longitudinal series of dorsal 
scales, 
12. Gerrhonotus ceruleus. (Tab. XXV. figg. A-D.) 
Gerrhonotus ceruleus, Wiegm. Isis, 1828, p.379 ; Dum. & Bibr. Erp. Gén. v. p. 397; Bocourt, Miss. 
Sc. Mex., Rept. p. 853, t. 21c. figg. 3. 
Gerrhonotus burnetii, Gray in Griff. An. King., Rept. p. 64; and in Beechey’s Voy. Rept. p. 96, 
t. 31. fig. 2 (bad) ; and in Cat. Liz. p. 54; Bocourt, 1. c. p. 356, t. 21 c. figg. 4. 
