254 ZONURIDE, 
and mucronate ; large, sharp, slightly curved spines 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 twenty-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- 
angular, the laterals feebly keeled and shortly mucronate. Two 
or three enlarged preeanal scales. Limbs above with large spinose 
imbricate keeled scales, inferiorly with smooth ones. Eleven 
femoral pores on each side. Upper and lateral caudal scales very 
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 spines not at all developed, and all tbe scales more 
strongly imbricate. 
millim. millim. 
Total length ...... 382 Fore limb .. 78 
Heads. coin kw 52 Hind limb........ 93 
Width of head .... 42 Mba fe ahiee eds Apu es 180 
Body asad oseenes 150 
South Africa. 
a,b. & & yg. Interior of S. Africa. Sir A. Smith [P.].  (Types.) 
ce-d. g & yg. 5. Africa. Earl of Derby [P.]. (Types 
of Zonurus derbianus.) 
2. Zonurus tropidosternum. 
Zonurus tropidosternum, Cope, Proc. Amer. Philos. Soc. xi. 1869, 
p. 169. 
Head-shields excessively rugose, with longitudinal strie ; rostral 
in contact with the frontonasal, which is much longer than wide and 
separates the nasals, and well separated from the frontal by the 
preefrontals ; 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. Pra- 
