356 Alexander Petrunkevitch, 



is especially true in the case of orbweavers and Th'eridiids. I have 

 Seen as many as eight males of Latrodectus madans in a sing-le web 

 tog-ether with one female, in San Geronirao on the Isthmus of 

 Tehiiantepec where this species is very abundant and is found 

 chiefly upon the cactus. Yet courtship in spiders is natural ly 

 hazardous, since it is always doubtful whether the female will meet 

 the male in a friendly way. In the case of the hunting- spiders 

 the male therefore as a rule, begins his courtship from a safe 

 distance, dances, beats rapidly on the ground with his anterior legs, 

 rises on the bind legs or walks head downward — a diiferent mode 

 of courtship characterizing each species — but he never stops 

 watching the female and takes to his heels at the first sign of 

 danger. Cannibalism is only too common among spiders. A robust, 

 hungry female does not recognize her mate in the male unless she 

 is sexually excited, looking on him only as prey ; but when she has 

 had sufficient food and is sexually excited, the latter condition 

 depending largely upon the maturity of the eggs and the temperature 

 of the atmosphere, then the male is allowed to approach, Now 

 begins the second act of the courtship, in which the sense of sight 

 plays no further role and both sexes are guided by the sense of 

 touch alone. With the decreasing resistence of the female, the 

 male becomes bolder and more aggressive until the reticence of the 

 former is overcome and the palpus is introduced into the genital 

 opening. In rare instances, as for example in the north American 

 Dendryphanfes marginatus (Walck.) (= Phüaeus müitaris Peckham) 

 the male builds a bridal tent over the immature female, and keeps 

 her there for several days, until she will emerge mature from her 

 last moulting when the mating will be possible. But whatever the 

 mode of the courtship may be, whether the spider is a sedentary 

 or a hunting one, there takes place always a remarkable and sudden 

 change in the instincts of the male when he attains maturity. This 

 is true for all genera and for all families. Ontogenetically older 

 and more general instincts are inhibited or superceded by new, 

 temporary instincts and the male performs actions which be has 

 never before performed and which, with the exception of some 

 species, he will never repeat. The change in the structure of the 

 bod}^ necessitates the change of all previous habits. 



The Theraphosid spiders in many respects present a distinct 

 and interesting group and for this reason I have for several years 

 sought an opportunity to study their structure and habits. Their 



