134 AMERICAN SPIDERS 



tree. This it lines with silk, then prolongs the silken lining up the 

 side of the tree. The aerial tube (Plate 15) is securely fastened to 

 the bark by threads, and in full-grown females is about ten inches 

 long and three fourths of an inch wide. Smaller specimens spin cor- 

 respondingly smaller tubes, which are almost invariably placed up- 

 right against a tree. The top of the tube is open, but the silk is so 

 flattened and pressed together that the natural opening seems to be 

 closed. An even covering of sand and other fine material serves to 

 color and darken the white silk and make it less conspicuous. In 

 Florida the tubes are most often found attached to sweet gums, 

 oaks, and magnolias in deep forest where the soil is damp and rich 

 in organic material although they have also been observed in dry 

 woods where the sandy soil has little or no covering of humus. 



In Atypus bicolor, a large spider shown in Plate XIII, the tubes 

 of old females are often eighteen inches long. This species occurs 

 from Maryland south into western Florida, and westward into Mis- 

 sissippi. They live for the most part in mesophytic woods. Near 

 Quincy, Florida, I found them abundant in deep woods near a small 

 stream. 



The tube of Atypus takes form in a characteristic manner. The 

 female spins a small, horizontal funnel or cell on the surface of the 

 soil, and from this base works both upward to lay out the aerial 

 tube, and downward into the soil. The funnel is pierced above, 

 and a two-inch section of vertical tube is set up against a tree. This 

 design is accomplished by laying down many single lines and spin- 

 ning the whole together into a strong fabric. The spider then 

 begins excavating and spinning the subterranean part of her habita- 

 tion. She molds the soil into small pellets, which she disposes of 

 through the opening at the top of the aerial web. The covering 

 of debris over the surface of the tube comes, surprisingly, from 

 within the burrow instead of being laid on from the outside: the 

 sand and small particles are pressed outward through the web until 

 the whole surface is evenly covered. After the first section of aerial 

 tube is completed, another length is spun and coated with sand. 

 Thus by sections the web moves up the side of the tree, until it 

 attains the full length for the species. Like an iceberg, the finished 

 tube penetrates the ground much farther than the length of its 

 visible, aerial portion. It is heavily lined with silk, which becomes 

 stronger day by day as the spinnerets constantly lay down their 

 dense bands. 



The European species of Atypus have habits similar to our 



