I have taken adult spiders, notably a Latrodectus scelio, 

 and kept them alive in captivity for periods of up to over two 

 years, during which time they certainly increased in size. 



I think it may reasonably be concluded that some of the 

 larger species live for three or possibly four years, which might 

 account for the difference in size. 



I have measured adult specimens of Mi-turga lineata which 

 varied nearly as much as the above. 



L. Koch describes two black species of Gasteracantha, G. astrigera 

 and G. lugubris, which differ from G. minax, Thor., firstly in the 

 absence of the characteristic white or yellow markings, in one 

 case from the back only and in the other both upper and under 

 sides, and, secondly, in the size and shape of the spines. On 

 looking over a large number of specimens of G. minax, a 

 numerous and widely spread species, it is quite easy to form a 

 series with spines varying from the most formidable dimensions 

 down to the finer and smaller as described for the black, which 

 are scarcer, though still widely spread. I have no males of the 

 latter, but in the females the genital structure is the same, and I 

 have, therefore, treated them as varieties only of G. minax, with 

 the melanism more or less complete. 



