114 



SCIENCE, 



[Vol. IV., No. 7a 



We hope the standard of the new president 

 from the West will be quality first, and quan- 

 tity afterward. Although in one sense he can 

 hardly equal the success of this year, a higher 

 kind of success desired by those who voted for 

 him is possible. If he has the strength and 

 wisdom to make it against all the solicitations 

 which will tempt him, the most important new 

 departure since the association was founded 

 may be quietly made next year, even by a very 

 small convention, in which quality shall be 

 made the touchstone of all. 



A BURROWING SPIDER. 



In the somewhat heavy soil of certain fields, 

 where but a scanty herbage thrives, the cave- 

 making spider (Tarantula arenicola, as iden- 

 tified by the Rev. Dr. H. C. McCook) has 

 excavated so many of the nearly perpendicular 

 and cylindrical burrows, that the place is almost 

 hone} T combed, and the surface is conspicuously 

 dotted by the irregularly five- sided towers 

 erected above each opening. The burrows 

 vary from one-quarter to three-quarters of an 

 inch in diameter, and in depth from eight to 

 twelve, or even twent}', inches ; the smaller 

 being formed, it is said, by the young, which 

 enlarge them with their growth. The walls are 

 compact and smooth, but without lining. Tow- 

 ers in other localities have been observed two 

 inches high : none I have seen are above one 

 inch, the majority being still less. 



Among my captives, the most active work- 

 ers are an adult and a half-grown individual, 

 between whose actions, while digging, slight 

 differences are observable. In a glass jar they 

 refused to do more than attempt to escape by 

 unavailing efforts to scale the sides, but, when 

 set free in the garden, the}^at once began to 

 exhibit their manner of burrowing, and dispos- 

 ing of the excavated earth. Most of the labor 

 is performed by the large and strong mandi- 

 bles, with the probable assistance of the fore- 

 legs. A pellet of earth, frequently a third of 

 the worker's cephalothorax in bulk, is loosened 

 as the spider labors head downward, and is 

 seized by the mandibles. The young spider turns 

 at the bottom of the burrow, and ascends, head 

 first, to the edge of the aperture, where the pel- 

 let is held just above the surface ; then, by a 

 blow from both fore-legs, it is thrown to a dis- 

 tance varying from four to twelve inches, usu- 



ally falling in particles, so that no fresh earth 

 is noticeable near the burrow-entrance. The 

 half-grown individual then backs down the tube, 

 and resumes work below. The mature spicier, 

 while the pit is shallow, ascends backward with 

 the load, comes entirety out of the orifice, turns 

 around, and, having popped the abdomen into 

 the opening, throws away the pellet. She rests 

 for a few moments, again turns within the 

 cave, and descends, head foremost. Before 

 returning to work below, however, she often 

 carefully examines the edges of the burrow- 

 entrance, and, if the earth has become dry 

 and friable, strengthens it by threads of web, 

 applied by longitudinal strokes of the spin- 

 nerets ; and, if her movements have broken 

 down the margins, she places her head under 

 the edge, pushing and lifting the earth in a 

 way suggestive of a dog's method of heaping 

 dirt on a bone with his nose. She then applies 

 more web, and resumes her digging. But, as 

 the burrow deepens, the mature spider also 

 turns while below. I have, however, never 

 observed a 3'oung individual bring up a pellet 

 backward. 



That the spinnerets of this species take an}* 

 part in pellet-making is improbable. Mrs. 

 Mary Treat, while studying Tarantula turri- 

 cula, observed their application to the earth- 

 mass before its ejection. It is likely that 

 Tarantula arenicola relies solely on the cohe- 

 sion of the moist particles, without the addition 

 of strengthening web, as I have repeatedly 

 witnessed the dry soil of the field crumble to 

 sand before the spicier could get the pellet 

 quite out of the tube. 



The young specimen brought up a load at 

 intervals varying from two to five minutes ; and 

 a cavern half an inch across and about one inch 

 deep was excavated in an hour and a half. 

 While deepening a burrow, a young spider in 

 the field worked somewhat faster. Assuming 

 a pit to be of the uniform width of three-quar- 

 ters of an inch and twelve inches deep, the 

 Tarantula must carry out the comparatively 

 enormous amount of 5.31 cubic inches of earth. 



The towers are usually composed of short 

 pieces of grass (fig. 1) placed above and 

 across each other in an irregularly five-sided 

 wall. Occasionally small twigs are used. In- 

 deed, almost any light object will be utilized if 

 within reach, for the spider will not leave the 

 burrow to search for materials. If nothing is 

 attainable without such an effort, she will erect 

 a low wall of earth. In several instances tow- 

 ers have been destroyed, and the ground cleared 

 for a space of three inches radius ; and from 

 another place the sod was removed: but, in 



