156 



AMERICAN SPIDERS AND THEIR SPINNINGWORK. 



on the 

 Orb. 



It loves the neighborhood of water, but is found distributed widely 

 througliout the meadows and in the foliage of bushes and low trees. Its 

 snare is of a delicate texture, finely spun, as a rule, but oftentimes short 

 and straggling. It is placed either in a vertical, horizontal, or inclined 

 position, but its general habit is horizontal, and with tliis class of Orb- 

 makers I have })laced it. It is armed with a pair of formidable jaws, whose 

 immense teeth and long fangs would appear to give it a great advantage 

 in its conflicts with enemies and efforts to secure food. 



In construction the orb of Tetragnatha extensa, as well as all other 

 species of the genus, corresponds very closely with that of the Orchard 

 spider. The hub is open, and a series of notched concentrics follows ; then 

 comes the free space; then the spiral space, the foundation space, and the 

 foundation lines. ^ 



The position of Tetragnatha is underneath the central part of her 

 snare. Her body is usually stretched across the open hub. The legs do 



not radiate from the body at open 

 angles, but are drawn very 

 Position qIqqq to the cephalothorax 

 at the fore part, and to the 

 abdomen at the hinder part 

 of the body. The fore feet clasp the 

 radii at or beyond the notched zone, 

 or one foot holds fast to a line which 

 is stretched to the under part of the 

 web and bows downward to the foot. 

 The abdomen, as in the case of the 

 Orchard spider, is hitched by a sim- 

 ilar line to the orb. In this position the spider sometimes swings almost 

 free from direct contact with her snare. The fore legs touch or approx- 

 imate near the middle, and the feet are curved outward. In spite of its 

 somewhat awkward appearance, Tetragnatha is remarkably lively in its 

 movements. 



When alarmed, Extensa runs down into the weeds or grass, and stretches 

 herself along the stem on which she has found refuge. Her legs hug 

 her body closely, even more closely than when suspended to her web as 

 just described. As her entire body is of a greenish yellow color, not 

 greatly different from that of the plant, it is somewhat difficult to distin- 

 guish her from the stem on which she rests. This peculiarity is well 

 known among observers of the species wherever it is found, and is cited 

 as one of the examples of protective form mimicry. 



^Description of Orha. No. 1. Vertical; 5x4 in. ; n. /., \ x \ in.; f. /,., ;[ x j in.; linl> iri-ct;n- 

 lar meshed work. No. 2. 5 x 5 aboiit ; f. z., i to f in. ; hub open, with few irreuular threads. 

 No. 3. Nearly vertical; 3 n. sp. ; r. Ki ; sp. 21 below, 15 above. No. 4. Horizontal ; 4.> x 5 in.; 

 r. 22, sp. 13 and less above ; n. z., 2 x .> ; f. z., 2 x I ; open hub. Nos. 5, 6, 7. Orb inclined about 45° ; 

 small, 3 to 5 in. in diani. Several orbs 2 in, diam. 



Fig. 148. Tetragnatha outstretched beneath the hub 

 of her snare. 



