222 re;ports of investigations and projects. 



from the center up to the nest ; also on those which build an open-sector web, 

 Zilla atrica and Bpeira aureola. Dr. Porter found an Bpeira cavatica 

 making alternately open and closed webs. It habitually makes a closed web. 

 Other Epeirse either make open webs or they are soon torn so as to appear 

 as such. Zilla as a species makes open-sector webs, but individuals may be 

 found with webs entirely or partly closed. One of two Bpeira aureola, both 

 followed each day for weeks, built a partly closed web. On pulling the large 

 nest down so that it and the signal thread was farther away from the web 

 (thus artificially bringing about the relations noted in those of the Zilla webs 

 which were solid) it was led to make the web less open. We seem to 

 obtain here a clue to the origin of the open-sector web, as well as evidence of 

 very great variation. 



Some 34 Zilla atrica spiders were brought from Gloucester, Massachu- 

 setts, to Shawnee-on-Delaware, Pennsylvania. Some were found to build 

 closed webs. Very hard rains and cool weather interfered with the attempts 

 to follow them as long as had been hoped. 



The correlation of variations in the web-making and cocoon-making 

 instincts is the subject of immediate concern. Some 700 cocoons, chiefly 

 riparia, have been collected in the last few days. Previous work with these 

 cocoons suggests that there may be important facts in the life history of 

 spiders, at least the Argiope, which are not yet known. 



The rains coming at about the break of dawn show many webs left un- 

 finished at about the same stage of completion. Spiders building webs in 

 protected places complete them. Bpeira sclopetaria have been observed to 

 emerge from their nests at about the same time in the evening. 



Interesting additions have been made to the observations previously pub- 

 lished on the mating of Argiope. As many as 10 males may attempt to 

 mate with a single riparia female. Specimens are now being prepared for 

 microscopic study to determine whether copulation is structurally impossible 

 until the female molts. From the behavior of the males and the structure 

 visible to the naked eye the writer has deemed it worth while to follow this 

 further. Tests in two cases point to the fact that the successful male dies 

 during the first few minutes of copulation. Unsuccessful males to the num- 

 ber of three or four are killed in their later attempts to copulate with the 

 same female. Later these may be eaten by the female or other males. 



In order not to deplete too much the supply of spiders for another year, 

 only a limited number of spiders of riparia, both male and female, was col- 

 lected and preserved during this past season. This will limit for the present 

 the study of variation in size of parts and color markings. It is the in- 

 tention to csiVTY this much further another season. 



