93 
Notwithstanding; the wide difference in size between the larger and 
smaller species ot this subgenus, it is absolutely impossible to make a fur¬ 
ther subdivision of the group, since no characters exist upon which to 
found such a distinction. Indeed, each species presents greater variations 
ot size and proportions dependent on sex than exist between the majority 
ot the species. For example, in JS r . eooperi , one of the larger species, the 
maximum measurements are:—Wing, 11.00; tail, 10.50; culmeu, 0.80; 
tarsus, 2.8a ; and middle toe, 1.85; while in N. fuscus, one of the smaller 
species, the minimum isWing, 6.35; tail, 5.50; culmeu, 0.35; tarsus, 
. ° ’ mu ‘dle toe, 1.10, an average difference of nearly one-half in dimen¬ 
sions between the female of eooperi and the male oifuscus; but reversing 
W? A sex ®f’ we ^ ave ? us the minimum measurements of eooperi: —Wing, 
^.<0; tail, 7.80; culmeu, 0.58; tarsus, 2.30; middle toe, 1.45; and as the 
maximum of fuscus: —Wing, 8.80; tail, 8.20; culmeu, 0.60; tarsus, 2.30; 
middle toe, 1.55—the conspicuous difference being thus completely lost. 
As regards proportions ot the toes, the male of eooperi and the female 
ot fuscus (typical representatives of the two extremes of size) have the 
inner toe reaching to a little beyond the first joint of the middle toe; 
but, in the male ot fuscus, it falls considerably short of the first articu- 
ation. The latter has usually the scutellm fused into a continuous 
plate; but the female, particularly in the immature stage, has the scu- 
tellie very distinctly defined. The latter condition is almost universal 
in eoopeyi; but an adult male in our collection (No. 2554) has as com¬ 
pletely “booted” a tarsus as any example of fuscus we have seen. 
The sexual differences in plumage are inconsiderable, or, practically, 
11 ( ? t t li e \ o u n g and old are entirely different in colors 
and markings, there being usually no resemblance whatever, except in 
the tail, which is much, the same at all ages in each species. It is this 
fact, and the lack of any other available character to answer the pur¬ 
pose, that has induced us to attach so much importance to the tail- 
bands in our key to the species. 
The following table of measurements wifi serve to show the compara- 
tnesize of the species as well as the limits of variation in each. A 
wider range would doubtless be shown iu several of these had we a 
larger series for measurement, there being iu the annexed table one or 
two instances where but one sex is represented. 
Comparative measurements of American species of Nisus. 
Wing. 
Tail. 
Culrnen. 
Tarsus. 
Middle toe. 
1. Nisus eooperi. 
8. 70-11. 00 
8. 25- 9. 90 
8. 50-10. 50 
8. 60-10. 50 
8. 10-10. 40 
8. 00-10. 00 
6. 80- 8. 40 
7. 80-10. 50 
7. 65- 8. 50 
6. 80- 8. 50 
7. 50- 9. 50 
6. 80- 9. 00 
7. 20- 8. 80 
6. 00- 7. 30 
2. 30-2. 85 
2. 25-2. 65 
2. 40-2. 65 
2. 50-2. 75 
2. 20-2. 65 
2. 25-2. 70 
1. 90-2. 25 
1. 65-2. 20 
1. 55-2. 00 
1. 95 
1. 45-1. 85 
1. 40-1. 70 
2. Nisus chilensis. 
3. Nisns guttatus. 
0. 50-0. 70 
0. 60 
0. 68 
0. 50-0. 70 
0. 55-0. 75 
0. 40-0. 52 
0. 35-0. 55 
0. 35-0. 45 
0. 45 
4. Nisus gundlaehi. 
5. Nisus nileatus. 
6. Nisus oicolor. 
i.35-i.’70 
1. 45-1. 80 
1. 30-1. 55 
7. Nisus cbionogaster. 
8. Nisus ventralis. 
9. Nisus ervthrocnemis 
5. 40- 6.20 
6. 30 
5. 50- 8. 20 
6. 90- 7. 00 
4. 80 
1. 10-1. 50 
1. 10-1. 40 
1.30 
1.10-1. 55 
1. 45-1. 50 
10. Nisus nigroplumbeus... 
6. 75 
11. Nisus fuscus. 
12. Nisus salvini. 
13. Nisus fringilloides. 
7. 60- 7. 80 
6. 25 
0. 50 
1. 85-2. 30 
2. 15-2. 20 
1. 80 
--- 
! 
The following key to the species is the best we have been able to 
devise from very complicated and variable characters presented. The 
characters common to all the species are the following:— 
Co3010 N CHARACTERS.— Tail crossed by wide bands of blackish and 
