6 o 
General Notes. 
[ January 
distinct groups, each distinguished by a particular style of coloration, and 
composed of two species, one of which is an ahnost exact miniature 
of the other. This curious, and So far as I know unparalleled, case may 
be illustrated by the following tabular statement: — 
Group I. Color above, bluish plumbeous; throat and collar round neck, 
white; a plumbeous pectoral band, behind which there is more or 
less of rufous, at least in the female. 
Larger species, C. torquata (Linn.). 
Smaller species, C. alcyon (Linn.). 
Group II. Color metallic bottle-green above, the throat and nuchal col- 
lar, white ; a bottle-green pectoral band, behind which there is 
more or less of rufous in the female. 
Larger species, C. amazona (Lath.). 
Smaller species, C. americana (Gm.). 
Group III. Color above, metallic bottle-green, the throat and nuchal col- 
lar, orange-ochraceous ; lower parts rich orange-rufous, the male 
with a pectoral band of white and dark-green bars. 
Larger species, C. inda (Linn.). 
Smaller species, C. superciliosa (Linn). 
The curious nature of the case involves several other facts which may 
furnish rich material for investigation to those engaged specially in the 
study of the origin of species and the various problems connected there- 
with. 
In the first place, the difference between the “homochromatic” species 
(if such a term may be used for those resembling one another in color), 
decreases in regular ratio from Group I to Group III; in other words, 
while the difference in coloration between C. torquata and C. alcyon is 
very marked (so far as the lower parts are concerned), the differences of 
coloration between C. inda and C. superciliosa are confined to the merest 
details ; while C. amazona and C. americana differ from one another less 
than do the species of Group I, but more than those of Group III. 
Scarcely less curious is the circumstance that between the largest species 
of Group I (C. torquata ), which for size may be compared with an Ivory- 
billed Woodpecker, and the smallest of Group III, which is scarcely larger 
than a White-bellied Nuthatch, there is a regular gradation in size, the 
species standing thus, in the order of their relative dimensions. 
C. torquata 
C. alcyon , 
C. amazona 
C. americana , j 
C. inda . 'i 
~ , ., . Group III. 
C. superciliosa , j 
Group I. 
> Group II. 
As another noteworthy fact, it may be stated, however, that 2 and 3 on 
the one hand, and 4 and 5 on the other, are more nearly equal in size than 
are 1 and 2, 3 and 4, or 5 and 6. — Robert Ridgway, Washing-ton, D. C. 
