EXPLANATION OF THE DIAGRAMS 



In the Figs, i, 2, 3, 6 and 8 the axes of the eyes are represented by dotted lines, the maximal angles 

 of vision and the plane of symmetry by common black lines. In the Figs. 4, 5 and 7 the heavy black 

 line represents the horizontal plane for the upper part of the figures and the plane of symmetry for the 

 lower part of the same figures. The axes of the eyes and the maximal angles of vision in these figures 

 are represented by common black lines for the mature spider and by heaN'y dotted lines for the young 

 spiderling. 



Plate I 



Fig. I. Phidippus tripunctatus, adult female. Projection of the eye-group on the horizontal plane 

 showing the axes of the eyes and the maximal angle of vision for each eye. 



Fig. 2. Lycosa nidicola, adult female. Same projection as in the preceding figure. 



