22 ZOOLOGY OF THE VOYAGE OF THE BEAGLE. 



of the former species in general form and arrangement, excepting that they are smaller and 

 less elevated. Those beneath the anterior part of the lower jaw are much smaller ; but the rest 

 on the under parts are similar to the former. 



The head is of a dull light-brown colour, with a few obscure darker spots. The general 

 ground colour of the back is " bluish gray, tinged with rust colour ;" there are five transverse 

 bands across the back, which are composed principally of numerous, close, small, dark- brown 

 spots, on a bluish-gray ground, darker than the intervals, and without any red tinge ; and each 

 band is marked on the posterior margin with strongly defined semilunar indentations, bordered 

 with yellowish-white, or bright yellow. These bands are continued on the tail, where they 

 become half-rings. 



DIMENSIONS. 



Inches. Lines. 



Length of the head ... l 2 



ofthebody 2 9 



ofthetail 3 5 



Total length ... 7 6 



Length of anterior extremity 1 4 



of posterior extremity 2 1 



Genus— AMBLYRYNCHUS. Bell. 



Amblyrynchus Demarlii. Bibr. 



Plate XII. 



Crista supra cervicem elevatiore, supra dorsum humiliore ; tuberculis verticalibus sub- 

 depressis, occipitalibus conicis ; caudd tereti. 

 Amblyrynchus Demarlii. Bibr. Hist. Kept. IV. p. 197. 



This species was first described by Mons.Bibron in the "Histoiredes Reptiles," 

 and so fully as not to require any detailed account of its characters here. It has 

 not, however, hitherto been figured, and it is thought very desirable to embrace so 

 good an opportunity of giving a representation of so interesting an animal. Its 

 most important structural peculiarities will be alluded to in the account of the 

 next species, which is an aquatic form, whilst the present is strictly terrestrial. 

 The toes are long, compared with those of the other, and so unequal as to consti- 

 tute essentially an ambulatory form. 



By Mr. Darwin's observations we are now enabled fully to confirm Mons. 

 Bibron's suggestion, that this species was from the Galapagos, and to establish 

 the genus as strictly appertaining to that curious and interesting locality. 



