GERRHOSAUEUS TYPICUS. 



lower lip four, the last but one much the largest. Scales of back and sides 

 quadrangular, arranged in transverse rows, and each strongly carinated ; 

 the scales of the upper and lateral portions of the tail are of the same 

 form as those of the back, similarly arranged and carinated. Lateral dupli- 

 cature slightly developed, space between rami of lower jaw anteriorly with 

 four large plates, the two first the smallest ; throat behind these and the 

 breast coated with six-sided smooth imbricate scales, their greatest width 

 transversely, and all arranged in longitudinal rows. Plates of the belly 

 arranged in transverse rows, ten in each, of a quadrangular form, and 

 each row lying over the base of the one behind it. Preanal plates, 

 three in a single row, the middle one triangular, and its apex directed 

 backwards. Scales of under surface of tail smooth, broadest at base 

 tapered towards point, which is slightly rounded. Fore legs coated 

 with smooth imbricate scales more or less six-sided ; hinder legs anteriorly 

 and inferiorly covered with scales of the same description but larger; 

 posteriorly the scales are triangular and strongly keeled. Femoral pores 

 sixteen, large, and prominent. Soles of the feet covered with very small 

 somewhat oval scales. The toes of the fore feet short and slender, the 

 innermost one very short, the second considerably longer, the third the 

 longest, the fourth a little shorter than the third, and the outermost rather 

 longer than the innermost. The third and fourth toes of the hinder feet, 

 reckoning the great or inner toe one, are much longer than those of the fore 

 feet, and the third exceeds considerably in length the fourth ; the second and 

 outermost toes are also much longer than the corresponding ones of the 

 fore feet. 



DIMENSIONS. 



Inches. Lines. 

 Length from the nose to the base of 



the tail 4 e 



of the tail c 6 



from nose to meatus externus 9 



Inches. Lines. 



Length from nose to base of fore legs 11 



Distance between fore and hinder legs 3 



Length of fore legs to base of toes ... 9 



hinder legs to base of toes ... 1 2 



The colours of the two sexes nearly the same. 



The only specimens of this species which I possess were procured on the sandy plains 

 which occur immediately to the south of the mouth of the Orange River. Over the sand of these 

 plains they run with such extraordinary rapidity, that it is almost impossible for the eye to 

 follow them in their flight. The instant they are discovered they seek a place of concealment, 

 and that they generally find in the loose sand which is commonly found accumulated under the 

 shrubs with which the district is furnished. In this sand they burrow with amazing rapidity, 

 and it requires an experienced eye to trace their course in it, though that is seldom far below the 



surface. 



