ON PARTHENOGENESIS IN SPIDERS. 303 



parthenogenesis of Filistata ? " It may be remarked that Artemia 

 salina is an instance of this kind. A paper by Holmberg 

 (1878) has been inaccessible to me. 



It is generally held that the females of spiders are not ready 

 for coition until they have passed their final moult, and that not 

 until then does the copulatory plate, the epigynum, become fully 

 developed. However, Bertkau (1885) has shown that Atypus 

 picens oviposits several years in succession, and a moult occurs 

 (with change of the seminal receptacles) after the first years of 

 egg-laying ; he remarks that the same is probably true also of 

 Gnaphosa lucifiiga. This would show that spiders may undergo 

 moults after they are fully mature, and indeed it is very likely 

 that when the female lives several years, and this is known to be 

 the case in a number of species, she undergoes a moult each year 

 after reaching maturity, for moulting is a necessary integral part 

 of the excretory process. Then I (1903) have described the case 

 of a Lycosa bilineata (Emerton) {L. ocreata pulchra Montg.) that 

 copulated successfully on June 3, and on the following July 12 

 moulted. During the present year I caught a Filistata with a 

 cocoon containing young ; she moulted on July 2 and again on 

 August 28. These instances indicate that spiders may be 

 sexually mature before their final moults. 



But one can be sure that a female is immature when her epi- 

 gynum is still a small, smooth plate, and that when she is in such 

 a condition she cannot be impregnated. And during the course 

 of earlier observations on the mating habits I have noted that 

 males avoid females that are not mature. Accordingly, females 

 of Entelogynae found with their epigyna small and imperfect may 

 be considered virginal. 



During the spring of this year the common Lycosa relucens 

 Montg. was found in large numbers in the early part of March, 

 males and females running over the ground in a wood at Austin, 

 Texas. At that time very few mature individuals of either sex 

 were discovered, the greater number being one or two moults 

 removed from the mature condition. When they become full 

 grown they are rarely found running upon the ground in the day- 

 light, but then usually remain hidden under leaves and stones. 

 Twenty-two females were secured, some on the third and the 



