490 The American Naturalist. [May, 
ZOOLOGY. 
Web-Spinning Spiders.—The origin and evolution of web- 
spinning in Spiders is given hy Mr. R. L. Pocock in a recent number 
of Nature. His theory may be briefly outlined as follows : 
Granting the inheritance of silk-glands from an ancestor, the first 
step in the formation of web-spinning was the formation of the cocoon 
for the protection of the eggs. This is characteristic of all spiders. 
The next step would be to extend this protection about herself and the 
retreat in which the mother had sought refuge while watching over the 
incipient brood. An aperture would probably be left for ingress and 
egress, and so arises a rudimentary form of the tubular nest or web 
which may or may not become a permanent abode for the mother 
after the dispersal of the young. That this is the seeond step in the 
evolution of web-spinning seems supported by the fact that, with the 
exception of the cocoon, it is the most constant feature in the spinning 
industry of spiders. At this point there are two developments. Along 
one is a gradual ascent in complexity until a culmination is reached in 
the trap-door nest of the wolf-spiders (Lycoside) and the bird-spiders 
(Aviculariide) ; while the other leads to the webs which function as 
snares, of which the web of the Epeira probably represents the highest 
type. 
From a tunnel-weaver like the Drasside which spins a temporary 
retreat for its breeding season, there are gradations to the web spun by 
the common house spider, Tegenaria, as an adjunct to its tubular retreat, 
and thence to the highty specialized orb-weaving of an Epeir, by way 
of the Nephilengys, a tropical genus, whose net shows a scanty mesh- 
work of lines arranged radially and concentrically with respect to the 
mouth of the funnel. 
It would seem, according to the author, that the primary influence 
in guiding the evolution of the architecture of the tunnel-making 
species has been the necessity for the preservation of life and the avoid- 
ance of enemies; while the web has resulted from a struggle for food. 
(Nature, March, 1895.) 
Fishes of the Northwest.—During the summer of 1892, Mr. C. 
-H. Eigenmann obtained a series of collections of the fishes of western 
Canada and the northwestern United States. The collections were 
made at 25 different places and include material for a comparison of 
