350 ARACHNIDA—ARANEAE CHAP. 
not belong to the Epeiridae but to the cribellate Uloboridae, but 
its defective orb-web is so curious that it deserves a special 
mention. A single foundation-line is laid down, and from it 
four radu are drawn 
and are connected 
with cross lines, the 
snare constituting 
about one-sixth of 
a circle. From the 
centre of the incom- 
plete circle a thread 
proceeds to some 
more or less distant 
object, and on this 
the spider takes up 
its position, inverted, 
and hauls in the line 
Fic. 191.—A, Snare of Hyptiotes sebaue® B, enlarged till the snare is taut. 
view of the Spider, showing the “slack”? of the When the trembling 
hauled-in line. (After Emerton. ) 
of the line shows the 
spider that an insect has struck the net, it lets go with its fore 
legs, and the web, springing back to its normal position, entangles 
the intruder more thoroughly by its vibrations. When large 
insects are in question the spider has been observed to “spring ” 
the net several times in succession. HH. cavatus is common in 
the pine woods of Pennsylvania, but the only English species, 
H. paradoxus, is extremely rare. 
A remarkable spider has been discovered in Texas by 
M‘Cook, which, after building a horizontal orb-web, converts it’ 
subsequently into a dome (Fig. 192) of exceedingly perfect form. 
It isnamed Fpeira basilica, and has been the object of careful study 
by Dr. Marx, who observed the whole process of web-construction. 
Threads are attached at various points on the upper surface of 
the horizontal wheel, the central portion of which is gradually 
pulled up until the height of the dome is nearly equal to the 
diameter of its base. But the snare of this spider does not 
consist of the dome alone. A sheet of irregular lines is stretched 
below, while above there is a maze of threads in the form of a 
pyramid. Several other Orb-weavers, as, for instance, £. laby- 
rinthea and E. triaranea, supplement their typical webs by an 
