1887.] NATURAL SCIENCES OF PHILADELPHIA. 877 



while in the act of feeding upon a locust a second individual 

 approcached near enough to be seized It was put upon the ground 

 where it was held down until the spider, moving slowly around, 

 overspun and swathed it, evidently reserving it for future use. 



3. Spinning and Spinning tvork. The central space of the little 

 mound in the box was usually kept covered with a white sheeted 

 web, suggesting the idea of a rug, upon which the creature loved to 

 rest. If this were removed or covered over with dirt it was restored 

 by the spider in a little while. In the act of spinning, the long 

 inferior spinnerets were curved upward, and from the spinning tubes 

 along the exterior part gave out numerous fine threads. These were 

 attached to the ground by the downward motion of the spinnerets. 

 The abdomen Avas lifted up, the threads were thus drawn out, the 

 downward motion repeated, and simultaneously the end of the 

 abdomen with the spinnerets attached received a lateral motion 

 which caused the threads to be spread over the surface of the 

 ground. At the same time the animal slowly moved its whole body 

 around as upon a pivot, thus dispersing the silk over a circular 

 patch of the surface, about equal in diameter to twice the length of 

 its body, or to the spread of its legs. (See Fig. 2). At times a 

 web much more open in texture would be found spread more or 

 less freely over nearly the whole surface of the soil. 



It has been said that when the white central rug became soiled 

 by dirt or food debris it was soon over spread with a clean layer. 

 In course of time the top of the mound in "Leidy's" box became 

 thus covered with a thick mass of intermingled silk and clay which 

 I easily removed and have preserved intact. The piece represents 

 nearly the compass of the central rug, and is a curious compound of 

 intermingled soil and silk. It is a fact that the remarkable hinged 

 door which the trap-door sj^ider attaches to her burrow is made up 

 of alternate layers of silk and soil. If one were inclined to specu- 

 lation, or to a "scientific use of the imagination," he might raise the 

 inquiry: may not the the trap-doors spiders have found in some 

 such accidentally formed texture the original suggestion of her mud- 

 and-silk door? On the other hand, one might also wonder why the 

 tarantula and, in fact, other spiders with equal facilities of like 

 nature have not developed some trace of the same habit ? 



Two locusts were once placed in the box at a part where the 

 threads were numerous, one of which was soon entangled in the 

 spinning work and began to struggle for freedom. Tarantula was 



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