11. LACHESIS. 553 
23. Lachesis luteus. 
Trimeresurus luteus, Boettg. Jahresb. Offend. Ver. Nat. 1895, p. 111. 
Rostral broader than deep; nasal divided; upper head-scales 
very small, flat, juxtaposed, smooth on the snout and vertex; supra- 
ocular large; no internasals; 12 or 13 scales on a line between the 
supraoculars ; two or three small postoculars and a subocular, which 
is separated from the labials by two series of scales; temporal 
scales keeled; 7 or 8 upper labials, second forming the anterior 
border of the loreal pit, third and fourth large. Scales strongly 
keeled, in 23 or 25 rows. Ventrals 182-186; anal entire; sub- 
caudals 72-74. Yellow above, with a dorsal series of rhomboidal 
dark, black-edged spots partly confluent into a zigzag band; a 
lateral series of small spots; a blackish streak on each side of the 
head behind the eye; yellowish beneath, spotted and clouded with 
grey. 
Total length 945 millim.; tail 164. 
Loo Choo Islands. 
24. Lachesis purpureomaculatus. 
Trigonocephalus purpureomaculatus, Gray, 11. Ind. Zool. i. pl. 1xxxi. 
(1832). 
Trimesurus purpureus, Gray, Zool. Mise. p. 48 (1842), and Cat. p. 8 
(1849). 
carinatus, Gray, 1. ce. 
nee puniceus (non Bote), Cantor, Cat. Mal. Rept. p. 122 
1847). 
Siiken bicolor, Gray, Ann. § Mag. N. H. (2) xii. 1853, p. 392. 
Cryptelytrops carinatus, Cope, Proc. Ac. Philad. 1859, p. 340. 
Trimeresurus porphyraceus, Blyth, Journ. As. Soc. Beng. xxix 1861, 
p. 110; Zheob. Journ. Linn. Soc. x. 1868, p. 64; Stoliczka, Journ. 
As. Soc, Beng. xxxix. 1870, p. 218; Theob. Cat. Rept. Brit. Ind. 
p- 222 (1876). 
carinatus, Giinth. Rept. Brit. Ind. p. 386 (1864); Stolezka, 
l.c. p. 217 ; Fayrer, Thanatoph. Ind. pl. xiii. (1874) ; Theob. Cat. 
Rept. Brit. Ind. p. 221. 
-purpureus, Ginth. 1. c. p. 387. 
andersonii, Zheob. Cat. Rept. As. Soc. Mus. 1868, p. 75; Sto- 
liczka, 1. c. p. 216, and Journ. As. Soc. Beng. xl. 1871, p. 443; 
Fayrer, l. e. pl. xv.; Theob. Cat. Rept. Brit. Ind. p. 224. 
obscurus, Theob. Cat. Rept. As. Soc. Mus. 1868, p. 76. 
—— monticola, part., Anders. Proc. Zool. Soc. 1871, p. 194. 
purpureomaculatus, Bouleng. Faun. Ind, Rept. p. 429 (1890), 
and Proe. Zool. Soc. 1890, p. 86; W. Sclater, Journ. As. Soc. Beng. 
lx. 1891, p. 248. 
Rostral as deep as broad; nasal entire; upper head-scales very 
small, juxtaposed, convex or obtusely keeled; supraocular very 
narrow, sometimes broken up; internasals small, separated from 
each other by one or two scales; 12 to 15 scales in a transverse 
line between the supraoculars ; two or three small postoculars and 
asubocular, which is separated from the labials by two or three 
