162 AMERICAN SPIDERS AND THEIR SPINNINGWORK. 
under favorable environment, develop like behavior. Moreover, the query 
arises, whether from some such accidental occasions, often repeated, may 
not haye sprung such a perfect navigating habit as that attributed to 
Dolomedes fimbriatus, who makes for herself a raft of leaves united by 
threads of silk, and so navigates the fens of Northumberland, England, in 
search of prey. 
Like her congener Extensa, the Stilt spider has a wide distribution over 
ae the United States. It is dispersed throughout the entire belt of 
on Eastern and Middle States; and the collections of Dr. Marx locate 
it in Empire City, Colorado; Fort Bridger, Wyoming; Kanayah, 
Aleutian Isles; Sitka, Alaska, and as far to the northeast as Unga Bay, Lab- 
rador. 
III. 
The remarkably extended geographical distribution of these species of 
Tetragnatha, and especially of T. extensa, necessarily raises the question as 
to the effect of environment upon structure and habits. Through- 
Distribu- oyt the wide area alluded to, the habits of Extensa, as far as I 
Bk have been able to learn, are absolutely identical. I have studied 
and Habitthe spider at widely separated points in the United States, and 
have made some observations of its habits in Great Britain. I 
have also compared my observations with all recorded by European ob- 
servers to which I could have access. There is no essential variation in the 
testimony. The structure of the animal herself remains unchanged. ‘The 
character of her web is everywhere the same. Her cocooning habit, her 
pairing habit, and in short all her life economy appear to be wholly unaf- 
fected by change of climate, food, site, and elevation. It must be allowed, 
indeed, that much remains to be done in the way of carefully noting the 
habits of the species in the various localities at which it has been collected ; 
but the spider has been known for more than a century, and, in Europe 
particularly, has been studied by all arachnologists, and has had as much 
attention given to her as to any other species, with the exception, perhaps, 
of Epeira diademata. The aboye conclusion, therefore, may reasonably be 
regarded as accurate. 
In this respect, Tetragnatha extensa is not alone. I haye shown that 
in the case of our large representatives of the genus Argiope (A. cophi- 
naria and A, argyraspis) precisely the same facts obtain. (See 
Chapter VI.) From the rugged. winters of New England to the 
perpetual summer of Southern California, throughout the mount- 
ain regions of Pennsylvania, and on the broad stretches of the American 
plains, these spiders have been traced, and are found everywhere the same 
in structure and habit. 
To these may be added a large group of the genus Epeira, all of which 
are distributed over Europe, North America, portions of Asia, and probably 
Other 
Examples 
