24 
ZOOLOGY OF THE VOYAGE OF THE BEAGLE. 
Genus— LEIOCEPHALUS. Gray. 
Leiocephalus Grayii. 
Plate XIII.— Fig. 1. 
Crista dorsali elevatd; cauda suh-compressa ; squamis ventralibus rhoniboideis, Icevibus; 
margine anteriore meatus auditorii quadridentato ; squama occipitali magnd. 
Habitat, Galapagos Archipelago. 
Description. — Head, viewed from above, forming a nearly equilateral triangle, covered with 
irregular slightly raised scales. Supra-orbital ridge prominent, and covered with a series of 
elongated and imbricated scales. Occipital plate large, pentagonal, notched at its posterior 
margin. The anterior margin of the auditory passage is strongly quadridentate, from the 
existence of four long and rather narrow scales. Scales of the temple obtusely carinated, not 
imbricated ; those of the back strongly and acutely carinated and disposed in numerous rows, 
converging backwards towards the dorsal crest. Ventral scales rhomboidal, not carinated. 
Dorsal crest elevated, composed of flat vertical scales, so closely placed as to constitute an 
almost continuous line, extending fi’om the neck to the end of the tail. Tail somewhat com- 
pressed at the base, becoming nearly round towards the middle. Scales beneath the feet and 
toes carinated. 
Colour. — The colour of this species is thus stated in Mr. Darwin’s notes : — “ Upper part clove 
brown, passing into black brown with black spots. Sides slightly tinted with orange ; some of 
the scales of the crest near the head are white ; belly nearly white ; the whole of the throat 
before the fore legs glossy black. This is the most common variety in the Archipelago. The 
black spots are not unfrequently placed in waved transverse bars, and are sometimes arranged 
longitudinally. 
DIMENSIONS. 
Inches. Lines. 
Length of the head 0 9 
of the body 2 8 
of the tail 5 8 
Total length 9 5 
Of this species, one of the most beautiful in the whole order of Saurians, Mr, 
Darwin obtained numerous specimens, one only of which is fully adult. In the 
younger individuals the dorsal crest is low and almost inconspicuous. It differs 
Tery materially from either of the two species previously described, and I have 
dedicated it to Mr. Gray, who first distinguished the genus. Mons. Bibron, un- 
aware that Mr. Gray had already constituted the genus under the name Leiocepha- 
lus, named it Holotropis. I have, however, retained the former name, as having 
the claim of priority. 
