how Spiders effect their aérial Excursions. 459 
longer than the posterior ones ; and it moves in a lateral direc- 
tion with almost as much ease and expedition as it does straight 
forward. The largest individuals of this species observed to be 
conveyed through the atmosphere by a current of air acting 
upon their lines, measured 3th of an inch between the extreme 
points of the head and abdomen ; -th of an inch across the 
broadest part of the abdomen ; and weighed about a quarter of 
a grain. 
'l'he second species has also four eyes of a greater magnitude 
than the other four. ‘The arrangement and relative size of three 
pair placed in the fore-part of the head may be thus expressed 
by dots *..: ; one of the other pair of large eyes being situated 
on each side of the head. Spiders of this species have the last 
pair of legs longer than the first, and move with great celerity, 
but rarely in a lateral direction. "They vary considerably in 
colour, some being of a much darker hue than others, and these 
are frequently without the pale longitudinal line which extends 
the whole length of the thorax, and sometimes even on to the 
abdomen of the lighter-coloured specimens. The largest indi- 
viduals seen floating in the air were somewhat inferior in weight 
and dimensions to the largest of the preceding species observed 
under similar circumstances*. 
* [s this the Aranea dorsalis of the Systema Nature, Gmelin's edit.? 
XXI. De- 
