566 VIPERID®, 
rostralis raised, forming a serration ; three series of scales between 
the eye and the labials ; loreal pit separated from the labials by 
small scales ; temporal scales keeled; 11 upper labials. Scales in 
21 rows, dorsals strongly or very strongly keeled. Ventrals 149- 
171; anal entire; subcaudals 41-49 pairs. ‘Tail prehensile. Olive 
or brown above, sometimes speckled with black, with a dorsal series 
of large rhomboidal dark spots or an undulous or zigzag band; a 
light, dark-edged streak from the eye to above the angle of the 
mouth ; belly yellowish or brownish, speckled or powdered with 
blackish ; a more or less distinct series of = spots along each 
side close to the ventrals. 
Total length 570 millim. ; tail 75. 
Mexico. 
a. Yg. (V. 149; C. 42). Orizaba. 
b-c. 6 (V. 166: C. 45) Omilteme, Guerrero. Mr. H. H. Smith [C.]; 
& yg. (V. 163; C. 49). F. D. Godman, Esq. 
d. & (V. 150; ©. 41). Oaxaca. M. Salis [C.]. 
36. Lachesis lateralis. 
Bothriechis lateralis, Peters, Mon. Berl. Ac. 1852, p. 674. 
Bothrops lateralis, F. Miill. Verh. Nat. Ges. Basel, vi. 1878, p, 401. 
Snout rounded, with moderately marked canthus. Rostral much 
broader than deep; nasal divided; upper head-scales moderate, 
imbricate, keeled, largest on the snout and vertex, 7 across between 
the supraoculars, which are narrow; internasals small, with 
smaller scales between them ; two series of scales between the eye 
and the labials; temporal scales keeled ; 9 upper labials, second 
forming the anterior border of the loreal pit, fourth and fifth 
largest. Scales rather strongly keeled, in 21 or 23 rows. Ventrals 
171; anal entire; subcaudals 59, single. Tail prehensile. Green 
above and below, with a yellow line running along the outer row 
of scales ; back with some black-and-yellow short cross-bars. 
Total length 485 millim.; tail 75. 
Costa Rica. 
a. 655) (Sc. 28; V. 171; Costa Rica, O. Salvin, Esq. [C.]. 
37. Lachesis bicolor. 
Bothro ye bicolor, Bocourt, Ann. Se, Nat. (5) x. 1868, p. 201; 
ill, Verh. Nat. Ges, Basel, vii. 1882, p. 155. 
—.- Sear: bernouillii, F. Mil. Verh. Nat. Ges. Basel, vi. 
1878, Seve l. iii. fig. A. 
Bothriechis bico or, Giinth, Biol. C-Am., Rept, p. 189 (1895), 
Closely allied to Z. lateralis, but upper head-scales smaller (10 
or 11 longitudinal series between the supraoculars), and 10 or 11 
upper labials not very unequal in size, the second not entering the 
loreal pit. Scales in 21 rows. Ventrals 164-167; subcaudals 
62-67, single. Uniform green above, yellowish beneath, 
