168 OPHIDIA. 
which I have examined, and which evidently belong to the same species, the extent of 
the preocular varies. 
As to Oryrhopus doliatus of Dum. & Bibr., this species is characterized by black 
rings completely encircling the body. I have never seen an example with this colora- 
tion, and the specimens described by me under that name (Cat. Col. Sn. p. 192) belong 
to a widely different species, viz. Coluber scolopax of Klein or Lycognathus scolopax otf 
Dum. & Bibr. 
Scytale coronatum (Schn.) is introduced by Cope into the Central-American fauna on 
the authority of Sternberg, who brought a specimen from Panama (Bull. U.S. Nat. 
Mus. no. 82, p. 76). 
LEPTODIRA. 
Sidon *, Fitzinger. 
Leptodeira (Fitzinger, n. n.), Giinth. Cat. Col. Sn. p. 165 (1858). 
Synopsis of the Central-American species. 
I. Scales in 19 series. 
A. Occipital not in contact with the labials. 
1. Hight upper labials . 2. 2. 2. 1 ww we eee ee ee LL nigrofasciata. 
2. Seven upper labials . . . . Lee ee ww we eR pacifica. 
B. Occipital in contact with the sixth labial toe ee eee ew ee 68. mystacina. 
II. Scales in 21 series. ; 
A. One preeocular reaching the vertical; ventrals 194 . . » . . . « 4 annulata. 
B. Two preoculars, the upper reaching the vertical. 
1. Collar not divided by a black line. Ventrals 189. . . . . . . 5. affinis. 
2. [Collar divided by a black line. Ventrals 192-211. . . . . . . 9. polysticia.] 
C. Preocular not reaching the vertical. 
1. Ventrals 180-1938 . 2. 2. 2... we we ee ee ee 6. yucatanensis. 
2. Ventrals 165-166... 2. 2 1. wee eee ee ww 7. splendida. 
IIT. Scales in 23 series. 
A. Chin-shields subequal in length. 
1. A white or whitish collar, not interrupted in the middle; ventrals 
168-176. . . . oe « « « . 8. personata. 
2. Nape divided in the middle by a “median dark line. 
a. Ventrals 192-211. 2. 2. 2... we ee ee we ew YD polysticta. 
b. Ventrals 165-170. 2. 2. 2. 2 1 ew ee ee ee ee. «102 ocellata. 
B. Posterior chin-shields much longer than anterior; ventrals 188 . . . 11. frenata. 
IV. Scalesin 25 series . . 2. 2... ee eee ee ee 12. rhombifera. 
* Linneus named a snake Coluber sibon, which, however, does not seem to enter the present genus. 
Moreover, Fitzinger’s definition of Sibon is extremely vague, and I prefer to retain the name which I chose for 
this genus in 1858. 
