98 Journal of Comparative Neurology. 



main sheet of the web under consideration to the main sheet of 

 the web above it. Gallery in angle. Guard web present, the 

 same height everywhere. Snares abundant. 



Example IX. — Location: angle between window sill and 

 side wall. Main sheet stretched from window sill to the side 

 wall. The sheet inclined, the side next to the window bemg 

 the lowest. Gallery in the angle. Guard sheet high, especially 

 so near the window. It would be difficult to find a more effec- 

 tive device than this for capturing flies that come gliding down 

 the window-pane. 



The observations recorded in e.xamples VII, VIII, and IX 

 were made upon the same species of spider, in the same locality 

 and at the same time. This fact gives the observations great 

 weight. It shows that, under similar circumstances, individu- 

 als of the same species occasionally arrange their webs quite 

 differently. Professor Morgan says that " Instinctive ac- 

 tions are those which are performed by the individual in common 

 with all the members of the more or less restricted group, in adapta- 

 tion to certain oft-recurring circumstances" If instinct be no 

 more than this, surely these spiders have transcended instinct. 



Among these triangular webs I have met with another in- 

 teresting modification. 



Example X. — Location: angle between a stone wall and 

 a vertical post. Main sheet triangular, attached in the angle 

 between the wall and post. Web nearly horizontal, bagging 

 slightly in the centre. Gallery in crevice between wall and 

 post. Snares fe>v, attached to both wall and post. 



The following is an extreme illustration of the same thing. 



Example XI — Location : angle between two walls. Main 

 sheet attached to both walls, in shape resembling an inverted 

 Japanese hat with a triangular brim. Numerous small bits of 

 whitewash were found in the depression. Gallery in the angle. 



It is a noteworthy fact that in both these cases and in other 

 similar ones, neighboring spiders of the same species had con- 

 structed webs that were approximately flat. 



At first blush, example XI appears to give us an exim])le 

 of a spider deliberately constructing an incline down which 

 struggling insects would roll to their doom. But I am not sure 

 that such an interpretation is warranted. The bits of whitewash 



