254 ZONURID^. 



and mucronate ; large, sharp, slightly curved spiues on the sides of 

 the neck. Dorsal scales large, forming regular transverse series, 

 rough, subquadrangular, with a strong keel ending in a short 

 sharp point ; twenty-three to twentj'-five transverse rows of scales 

 from occiput to base of tail ; the median series composed of twelve 

 scales, not including those on the flanks ; latter lanceolate, keeled, 

 spinose, separated by wide granular interspaces ; a slight lateral 

 fold. Ventral scales large, strongly imbricate, forming ten or 

 twelve regular longitudinal and twenty-five to twenty-seven trans- 

 verse series ; the median and pectoral scales smooth and subtri- 

 augular, the laterals feebly keeled and shortly mucronate. Two 

 or three enlarged praeanal scales. Limbs above with large spinose 

 imbricate keeled scales, iuferiorly with smooth ones. Eleven 

 femoral pores on each side. Upper and lateral caudal scales verj^ 

 large, strongly spinose, the lateral spines largest and horizontal ; 

 lower caudal scales long, narrow, pentagonal, smooth. Yellowish, 

 back clouded with brown ; upper surface of head brown. 



The young light yellowish, marbled and cross-barred with black- 

 ish-brown ; the s^Dines not at all developed, and all tbe scales more 

 strongly imbricate. 



millim. niillim. 



Total length 382 Fore limb 78 



Head 52 Hind limb 98 



Width of head 42 Tail 180 



Body 150 



South Africa. 



a,b. c? & vg. Interior of S. Africa. Sir A. Smith [P.]. (Types.) 



c-d. cJ & yg. S. Africa. Earl of Derby [P.]. (Types 



of Zonurus derbianus.) 



2. Zonurus tropidosternuin. 



Zonurus tropidosternum, Cope, Ej-oc. Amer. Philos. Soc. xi. 18G9, 

 p. 169. 



Head-shields excessively rugose, with longitudinal strioe ; rostral 

 in contact with the frontonasal, which is much longer than wide and 

 separates the nasals, and well separated from the frontal by the 

 prtefrontals ; the other head-shields as in Z. cordylus, except that 

 there are six rows of temporals ; upper labials six, the fifth not more 

 elevated than the others ; lower labials six, in contact with a row of 

 five shields. Gular scales in twenty-two series from angles of man- 

 dible ; those of the neck abruptly larger, mucronate, keeled, forming 

 a rudimental collar. Dorsal scales in twenty-four series from nape 

 to opposite femur, all strongly mucronate, keeled and rugose ; the 

 median series like the others. Median ventrals nearly smooth, 

 laterals mucronate, keeled. Lateral scales increasing regularly in 

 size from the ventrals, subround, widely separated from each other 

 by minutely granular intervals, strongly mucronate, keeled. Prae- 



