THE GENESIS OF SNARES. 341 
point at which the inward end of the line is fastened to the tent or stays. 
But this loop is only incidental, and serves no special purpose (as far as 
we know) in securing the entanglement of prey. But with the Triangle 
spider the coil is a prominent and special feature of the net. It is always 
found between the hind legs and the third pair of legs, and when the 
snare is sprung, as already described, this coil instantly straightens out, 
permitting the whole net to shoot forward, and the forward motion sends 
every line around the entangled victim and adds to the degree of its en- 
tanglement. 
When we consider the Ray spider’s habit we find the trapline here 
even more highly specialized. It has,-first, the uses common to the typical 
Orbweaver, that is to say, it serves for telegraphy and _ transi- 
er ,. tion. Second, it acts as a regular trap, inasmuch as it has a 
pider’s ier ; ; ; 
repli.” prominent coil of slack line ready to be sprung at any time. 
But, further, it unites all the separate sectors of the orb into one 
common system, thus serving not only to spring a single net, as in the case 
of Hyptiotes, but a series of united nets of the same sort. 
Moreoyer, this spider possesses the habit of moving its trapline from 
point to point, instead of keeping it fixed as in the case of the Triangle 
spider—certainly a remarkable adaptation. Further, by a simple but ingen- 
ious system of “locking” the web, that is, twisting the axis of the sev- 
eral rays around the extremity of the trapline, the spider causes the trap- 
line to hold her whole snare in workable position while she resorts to 
any part thereof to seize her prey. Thus, also, as the daily wear and tear 
in capturing food destroys in succession various parts of the web, the 
trapline holds together and intact the remaining parts, even though quite 
opposite to each other. 
We have thus traced the natural history of this important and useful 
member of the Orbweaver’s web, from a simple dragline by which the an- 
imal escapes from and returns to her snare, through an interesting series 
of variations, to this quite specialized and complex use which marks the 
trapping habit of Theridiosoma gemmosum. 
Thus, as a dragline it serves, first, the cautionary use of escape from 
danger by swinging to an anchorage; second, it affords a trail for retreat 
to the place of departure; third, it serves to telegraph agitation 
of the snare to the proprietor; fourth, it holds the snare taut, 
and thus maintains its efficiency; fifth, it acts as the spring line of a 
genuine trap; and, sixth, it binds and locks together the united or the dis- 
severed parts of a snare, which at the same time it also springs separately 
or together as need requires. Of course, I do not pretend to intimate that 
there has been anything like a development of the use of the trapline in 
the sense that there is any traceable genetic connection between the various 
adaptations here pointed out. So far as I know, and, perhaps, as far as 
ean be known, every species preserves its own habit quite independent of 
Summary 
