Skeletons of Recent and Fossil Gymnogyps— Fisher 
229 
the species under study. However, the data 
presented may also be of use in future studies 
of the tempo and mode of evolution as 
defined and studied by Simpson (1944). 
Acknowledgments: I wish to express my 
gratitude to Dr. George G. Simpson for 
many helpful suggestions, and to acknowl¬ 
edge the use of facilities at the Los Angeles 
County Museum and the Museum of Verte¬ 
brate Zoology, Berkeley, California, where 
much of the work was done. 
DISCUSSION OF MEASUREMENTS 
In Table 1 the measurements of the wing 
demonstrate that the mean wing length of 
am plus is 4 per cent greater than in calif orn- 
ianus; the maximum length in am plus is 8 
per cent greater, but the minimum lengths 
are about the same. It should be noted, 
however, that the entire range of wing 
lengths in californianus is within the limits 
of the range of am plus. Consequently, the 
species could not be separated on the basis 
of wing length, even if associated skeletons 
TABLE I 
Measurements of the Wing (mm.)* 
NO. 
spec¬ 
imens 
MEAN 
MAX. 
MIN. 
Humerus .... 
S 11 
267 
27 4 
262 
( 60 
276 
292 
260 
Ulna .......... ............ 
I 8 
313 
320 
305 
1 31 
322 
345 
304 
Metacarpus ............ 
f 3 
132 
133 
131 
(118 
139 
148 
129 
Digit II, phalanx 1 
\ « 
53.4 
54.0 
52.1 
l 74 
54.8 
60.5 
51.3 
Digit II, phalanx 2 
1 i 
43.9 
44.8 
43.4 
l 26 
50.2 
52.7 
47.0 
Total length .. 
f 
809 
826 
794 
l 
842 
899 
791 
* First row ^of figures under each category pertains to 
calif ornianus, the second row to amplus. 
of the fossil were available. A statistical 
study of the intramembral proportions of the 
wing shows no significant differences be¬ 
tween the two species. 
In no raw measurement (Table 2) of in¬ 
dividual humeri do the species differ; in the 
series the fossil form is always largest, but 
all the ranges overlap considerably. Signifi- 
TABLE 2 
Measurements (mm.) and Proportions of the Humerus* 
Total length. 
Greatest proximal width 
Greatest distal width . 
Length bicipital crest. 
Length deltoid crest . 
NO. 
SPEC¬ 
IMENS 
RANGE 
MEAN 
STANDARD 
DEVIATION 
COEFFICIENT 
VARIATION 
1 11 
262-274 
267 ± 1.2 
3.93 ± .84 
1.47± .31 
( 60 
260-292 
276± .95 
7.32 ± .67 
2.65 ± .24 
I 13 
48.2-53.3 
50.3± .42 
1.51± .30 
3.00± .59 
1 52 
50.2-57.5 
53.7± .25 
1.82 ± .18 
3.39± .33 
f 11 
45.0-49.0 
47.0 
( 59 
46.4-54.6 
49.8 
f 13 
47.1-52.2 
49.2 
( 50 
48.0-55.9 
51.6 
{ 12 
97-119 
105± 1.87 
6.47 ± 1.32 
6.16± 1.32 
l 59 
113-129 
120 ± .57 
4.4l± .41 
3.67± .34 
proportions of humerus 
Proximal width : length .. 
11 
18.2-19.6 
18.6± .13 
.44 ± .09 
2.33± .50 
1 52 
18.1-20.6 
19.5± .03 
.20± .02 
1.03± .10 
Distal width : Ienpth 
I 11 
16.7-18.6 
17.6 
( 59 
17.3-19.1 
17.8 
Bicipital length : length 
1 11 
17.9-19.0 
18.3 
( 50 
17.6-20.1 
18.8 
Deltoid length : length. 
11 
36.5-42.7 
39.2 ± .64 
2.12± .45 
5.4 ±1.2 
l 59 
40.4-46.8 
43.6± .16 
1.2 ± .11 
2.75± .25 
* Hrst row of figures under each category pertains to calif ornianus, the second row to amplus. 
