16. TRETANORHINUS. 281 
1. Hydrethiops melanogaster. 
poet melanogaster, Giinth. 1, c. pl. iii. fig. G. 
Heli oar marginatus, Fischer, Oster-Progr. Ak. Gymn. Hamb, 1883, 
—— lineofasciatus, Sauvage, Bull. Soc. Zool, France, 1884, p. 203 
pl. vi. fig. 3. 
Rostral as broad as deep, or a little broader, just visible from 
above and in contact with the internasal, which is triangular and 
Jonger than broad ; frontal a little longer than broad, as long as 
its distance from the end of the snout, shorter than the parietals ; 
loreal a little longer than deep; one pre- and two postoculars ; 
temporals 1+2 or 14-3; ten or eleven upper labials, fifth and 
sixth or sixth and seventh entering the eye; three pairs of chin- 
shields, the anterior in contact with five lower labials. Scales 
more or less strongly keeled, in 23 rows. Ventrals 143-154; anal 
divided ; subcaudals 39-49. Dark olive-brown above, with five 
more or less distinct series of alternating black spots; a yellowish 
stripe on each side, from the eye or the angle of the mouth along 
the first and second rows of scales ; lower parts black. 
Total length 610 millim. ; tail 100. 
West Africa. 
a-d. g (V. 151; ©. 48) & V. 147, Gaboon. (Types. 
151, 149; Ci, 89, 41), ° ) 
2 2 (V. 143; 0; 48). Cameroons, 
16. TRETANORHINUS. 
Tretanorhinvs, Dum. § Bibr. Erp. Gén. vii. p. 348 (1854) ; Jan, Arch, 
Zool, Anat, Phys. iii. 1855, p. 254; Bocourt, Le Naturaliste, 1891, 
p- 121. 
Helicops, part., Jan, l. c. p. 245. 
Maxillary teeth about 30, subequal; mandibular teeth subequal. 
Head slightly distinct from neck; eye rather small, with round 
‘ 
pupil; nostrils directed upwards, pierced between two nasals. 
Body cylindrical ; scales striated and keeled, without apical pits, in 
19 or 21 rows; ventrals rounded. Tail moderate ; subcaudals in 
two rows. Hypapophyses developed throughout the vertebral 
column, 
Central America and Cuba. 
Synopsis of the Species. 
Two prefrontals; posterior chin-shields 
separated from each other by scales ; 
OGM 20 TONS ow cccdr es vess.ccapac 1. variabilis, p. 282. 
‘Two prefrontals; posterior chin-shields 
in contact with each other anteriorly ; 
scales in 21 rows . .........04: +e+» 2. nigroluteus, p. 282. 
A single prefrontal ; posterior chin-shields 
in contact with each other anteriorly ; 
seales in 19 rows ......... seseesees od mocquardii, p. 283. 
-_— ee eee 
