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HORIZONTAL SNARES AND DOMED ORBS. 169 
horizontal one; and that it is lifted up gradually by attaching lines at 
various points upon the upper surface and drawing them taut, one after 
another, until the whole is lifted up into the domed structure represented 
in Fig. 154. I may add that Dr. Marx was also able to collect cocoons of 
the species, and describe the manner in which they are hung in the neigh- 
borhood of the web.1 
The manner in which this change is wrought was determined by Dr. 
Marx, and he has kindly placed at my disposal his notes upon the same. 
When first observed by him (at 8.30 A. M.), the snare lay in a horizontal 
plane, as shown at Fig. 158, and had more than fifty radii. It was hung 
between the tips of the branches of a bush. At 12 M. the borders of the 
snare were benf downward, causing it to assume the form of a shallow 
dome. At 4 P. M. the transformation had so far progressed as to bring the 
web to the structure represented at Fig. 159. The work was carried on in 
this wise: At the marginal edges were outgoing lines, as ¢ b, Fig. 
158, used to support 
or brace the snare, as 
is usual with hor- 
izontal orbs. On 
Fic. 158. Basilica spider’s mode of transforming a horizontal 
into a domed orb. 
these at certain points (c) were fastened lines (ce d), 
which were attached to a branch (d) some distance 
below and to one side of the plane. These lines 
(c d) were gradually borne downward until they 
sition of the dotted line, ab. This action caused the depression of 
the edges; and by continuing this manipulation of the outside or 
foundation lines, the orb was forced first into the shape of a shallow dome 
flattened at the pole, and then into the form of the typical web as above 
described. (Fig. 159.) This action was seen “repeated over a dozen times.” 
But it was manifest that some other method had been brought to bear 
than that already explained. The position of the snare in its original 
horizontal form had been exactly located by a fork (f, Fig. 158), in the 
branch to which the stay lines were attached, which was on a level with 
the horizontal axis of the orb. Now, however, the edges of the web were 
not only drawn below the level of the fork, but the central part was raised 
at least three-fourths of an inch above the fork. (Compare f, Fig. 158, 
with f, Fig. 159.) The manner in which this had been done was readily 
seen by a glance at the various lines, perpendicular and inclined, which 
assumed the po- 
1See Vol. II., Chapter on Maternal Industry. 
