1893.] The Color Variations of the Milk Snake. 1067 
the varieties of the lizard Cnemidophorus tessellatus and C. 
guitatus and those of Eimer on Lacerta muralis’ show distinetly 
the same phenomenon. 
Before going further into the patterns of the Ophibolus dolia- 
tus, I give a synoptic key of them. 
I. No yellow band posteriorly from orbit (a yellow half 
collar). 
a. Dorsal spots or saddles (red) open at the side, their adja- 
cent borders forming pairs of black rings. 
- Interspaces between red saddles open below ; scales not black- 
ri ial front more or less black; first black ring on nape 
nly O. d. coccineus. 
inate between red saddles closed by black spot below; 
scales black tipped; front black; first black ring complete. 
O. d. polyzonus. 
Interspaces not closed; rings including first complete on 
belly; first yellow band crossing occipital plates; front 
black ; scales not black-tipped O. d. conjunctus. 
aa. Dorsal saddle spots closed at the sides below. 
b. Saddles closed by asingle black tract on the middle of 
the belly; no spots between the saddles. 
Dorsal spots undivided medially ; front black; first black ring 
complete O. d. annulatus. 
Dorsal spots divided longitudinally by a median black con- 
nection ; front black O. d. gentilis. 
bb. Inferior borders of saddles separate and not confluent 
with each other. 
Saddles completed on gastrosteges; no alternating spots; no 
black collar O. d. parallelus, 
Saddles completed on gastrosteges; spots opposite intervals 
forming a single series on the middle line of the belly 
O. d. syspilus. 
Saddles completed above the gastrosteges; alternating spots 
which do not meet on the middle line of the belly 
O. d. doliatus. 
®Transac. Amer. Philos. Soc., 1892, p. 27. 
"Archives f. Naturgischichte, 1881. 
