24 ZOOLOGY OF THE VOYAGE OF THE BEAGLE. 



Genus— LEIOCEPHALUS. Gray. 

 Leiocephalus Grayii. 



Plate XHI.— Fig. 1. 



Crista doi'sali elevatd ; caudd suh-compressd ; squainis ventralihus rhomboideis, IcBvihus; 

 margine anteriore meatus auditorii quadridentato ; squamd occipitali magna. 



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 vfith 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 from 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. 

 CoLOUK. — 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 9 



of the body 2 8 



of the tail 5 8 



Totallength 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 

 very 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 Uololropis. I have, however, retained the former name, as having 

 the claim of priority. 



