188 



AMERICAN SPIDERS AND THEIR SPINNINGWORK. 



been made by a single mother. It struck him as a strange circumstance, 

 and he reported the fact to me. Only recently Mrs. Mary Treat has pub- 

 lished a description of what she considers a variety of this spider, Argiope 

 multiconcha, 1 which habitually makes as many as four and sometimes five 

 cocoons. I have one of these strings, which was made in a kitchen where 

 a great cooking stove was in almost constant use to supply the demands 

 of a large family. It contains four cocoons, which were hung close to 

 each other, and precisely in the manner of those of Basket Argiope, which 

 they exactly resemble. The habitat of this spider, as far as now known, 

 is Missouri. The animal itself differs very little from Cophi- 

 Argiope nar j a _ Unfortunately, the one specimen that I have seen was so 

 much dried up that it could not be figured, nor could any dis- 

 tinctive features be readily traced ; but it seems to differ in no 

 essential respect from Cophinaria. Thus, the interesting question emerges, 

 what are the conditions controlling this function in this spider? It can 

 hardly be quantity of food, as with Termeyer's Diademata. If it be qual- 

 ity, upon what meat does this aranead feed, that she should so excel her 

 congeners in cocooning industry ? A tropical spider, Argiope aurelia, it 

 may here be stated, according to Mr. Pollock, makes ten cocoons. 



V. 



The number of eggs within cocoons differs very much in different spe- 

 cies, and even among different individuals of the same species. Walckenaer 

 reports 2 that Epeira diademata has been found by him to con- 



tain from three to four hundred eggs, and again from six to 



Number 



of Eggs. 



eight hundred, a wide range of difference certainly. I have 



counted as many as eleven hundred and ten young spiders in the cocoon 

 of one Argiope cophinaria, and eleven hundred and fifty-two spiderlmgs 

 in another ; and this is probably near the normal number. Some females 

 lay many less; as low, at least, as one hundred and fifty. The Peckhams 

 give the number of eggs laid by this species as varying from five huudivd 

 to twenty-two hundred. According to Staveley, the cocoons of Argyroneta 

 aquatica range from forty to one hundred in number. 



The reasons for this varying fertility are not certainly known. They 

 depend, no doubt, upon the female's vital condition. A full measure of 

 health and abundant nutrition doubtless conduce to the normal number 

 of eggs, and this is probably diminished by physical weakness and lack of 

 nourishment. I believe also that the conditions surrounding the spider 

 influence the number of eggs, for females in artificial confinement seem to 

 deposit fewer than those in natural habitat. 



Spiders that make a number of cocoons, as a rule deposit few eggs in 

 every one, so that the aggregate of eggs laid is about equal to the number 



1 See "American Naturalist," December, 1887, page 1122. 2 Apteres, Vol. I., page 154. 



