372 SYNOPTIC COLLECTION. 



posterior pair of spinnerets. The genital opening (fig. 

 2,y) is at the anterior end of the abdomen, and on either 

 side of this opening there is a horny patch of skin which 

 marks the position of the two air sacs or lungs (fig. 2, /z). 

 Besides these lungs the spider is provided with air-tubes 

 or tracheae opening in a single spiracle, just in front of 

 the spinnerets (fig. 2, k). 



One of our largest spiders is the brightly colored Argi- 

 ope cophinaria Walck. ( = Epeira riparia Hentz) (No. 919, 

 9 , $ ), which is abundant in certain places along our 

 coast, no less than three hundred and forty having been 

 collected in an hour at Beachmont, Massachusetts. 



This spider hangs out from the middle of its web and 

 being brightly colored is a conspicuous object ; for this 

 reason it would seem that it would fall an easy prey to its 

 enemies. It has, however, protected itself in a most 

 ingenious way. On either side or in front of its web (PI. 

 920) it spins many irregular threads. The spider has 

 such a delicate sense of touch that if one but lightly 

 place his finger on a thread, "she falls like a shot to the 

 ground, where with her back down, and her legs drawn 

 in she is difficult to find, unless you have followed the 

 drop with your eye. Or approach the web without touch- 

 ing it ; your shadow, the sound of your footstep, or per- 

 haps the vibration of the ground warns her; still, the 

 danger does not seem imminent ; she has time to make 

 use of another power she will render herself invisible. 

 The web begins to sway backward and forward ; the 

 rapidity of the motion increases ; the outlines become 

 indistinct, and within a few seconds of the first move- 

 ment, spider, web and all have vanished from sight ! " l 



Another species of Argiope (No. 921, A. argyraspides 

 Walck., 9, <) from Long Island in Casco Bay, Maine, 

 is conspicuous tor its size, light color, and banded legs. 



1 Peckham, Occasional Papers, Nat. Hist. Soc. Wisconsin, I, 

 1898, pp. 72, 73. 



