1002 The American Naturalist. (December, 
increased the size of body and the length of legs to the south- 
ward, and shortened them in the north. The points of differ- 
ence indicated by Say and Wood prove without value when 
many specimens are examined. 
The harvest-spiders are well adapted for the study and illus- 
tration of organic variation. Their long legs are easily meas- 
ured, and the results can be set down in black and white, with 
more striking effect than in the case of most invertebrates. 
To determine the variability of the species in a given 
locality I measured seventeen fully developed males taken in 
the fall of 1889 at Columbus, Ohio. The results are shown in 
table I: 
This shows a striking and constant variation, the longest of 
the fourth pair of legs being one-third longer than the shortest, 
and the difference in the other legs being nearly as great. 
To determine whether similar variations occurred in other 
localities, six fully developed males, collected on the farm of 
the University of Illinois, were measured, with the results 
shown in Table II: 
The fact that there was a difference of ten millimetres in 
the length of the second pair of legs in the case of six 
specimens, selected at random, indicates that this amount of 
variation, at least, is normal to the species in that locality. 
Two fully developed males sent by Mr. J. M. Aldrich from 
Brookings, South Dakota gave the following measurements: 
ea 
TABLE III. LIOBUNUM VITTATUM DORSATUM SAY. MALE. BROOKINGS, SOUTH Dak. 
Noad [Measurements of body.| Mensurements |.) 4h 
Specimen salpi 
— 
— 
ja . 
Lan 
me 
=< 
| Length |Breadth| Height| I | I 
1 5 4 25 | 21 | 34 | 21 | 29 | 62 : 
pata Seka $5 | 23 | 19 | 85 | 19 | 26 | 61 | ae 
Average | ő 88 | 24 | 20 |845| 20 (275 616| 
——— 
In striking contrast to this are the following measurements 
of two fully developed males from Mr. H. E. Weed, collected at | 
the Mississippi Agricultural College: 
aa Sse ae sate eae ON pre 
Se he LE ES Ee a re or ir ie ft ee ee >a 
ARNT 
