380 SURG. J. C. THOMPSON ON THE 
in width in pyramidal fashion. ‘The shield regarded as the first 
gastrostege is the one that is nearly the standard width; it is 
frequently distinguished by having a colour similar to the rest of 
the ventrals and not white or cream like the throat. 
List oF SPECIES EXAMINED. 
Xenopeltis unicolor, p. 380. 
Polyodontophis geninatus, p. 380. 
Polyodontophis collaris, p. 381. 
Thamnophis ordinordes, p. 381. 
Tropidonotus vibakart, p. 384. 
Tropidonotus sauteri, p. 385. 
Pseudoxenodon sinensis, p. 385. 
Zamenis constrictor, p. 386. 
Zamenis rhodorhacis, p. 387. 
Zamens florulentus, p. 389. 
Coluber oxycephalus, p. 389. 
Philothamnus semivariegatus, p. 394. 
Cerberus rhynchops, p. 394. 
Leptodira hotambeia, p. 397. 
Psammophis sibilans, p. 398. 
Ophiophagus bungarus, p. 398. 
Doliophis bivirgatus, p. 400. 
Causus rhombeatus, p. 401. 
XENOPELTIS UNICOLOR Reinwavrdt. 
Specimen.—California Acad. Sci. No. 16750. Singapore. 
Adult female: total length 480, tail 58 mm. 
The vertebral artery arises from the right aortic arch at the 
AD5th g. and courses superficially to the 12th g. It gives off an 
intercostal branch to each vertebra, and these enter in the 
median line. The right aorta is nearly the same diameter as the 
left. It gives off eight intercostal branches; each arises as a 
single trunk which bifurcates midway to the parieties, and the 
forks enter on either side of the median line. The dorsal aorta 
begins at the 52nd g. The intercostal branches arise anteriorly 
as a single trunk which upon reaching the parieties bifurcates, 
one fork entering on each side. Before the gall-bladder these 
bifurcate nearer to their origin, and behind this organ they are 
symmetrically paired. The right kidney receives two renal 
arteries; the first enters the second lobe, and the second the sixth 
lobe. The left kidney receives one artery which enters at the 
second lobe. 
PoLYODONTOPHIS GEMINATUS Boie. 
Specimen. — California Acad. Sci. No. 16751. Botanical 
Gardens, Singapore. Adult male. 
The trachea enters the lung at the level of the 36th g.; it 
