Larva of Chaoborus Crystallinus ( de Geer). 
343 
on the most prominent and broadest part, but the thorax is much 
broader than the head. 
When the larva is viewed with the tail pointing towards the 
observer no eyes will be visible. A sight of any object approach- 
ing from the rear would therefore be impossible. 
This opened up the question as to the value of the eyes com- 
pared with other sensory organs — such as the hairs — in giving 
warning of approaching objects. 
There are instances in pond life where a pigment spot, with or 
B, hairs on the dorsal side of thorax of C. pallida ; A, E,|after Graber ; 
C, D, explained in text. 
without a lens, is all the creatures possess, having neither antennae 
nor hairs to assist in locating objects fixed or moving, and in many 
of such cases there is little attempt to evade an approaching 
pipette. On the other hand, a young Corethra will resort to all the 
dodges of doubling back and shooting here and there to avoid 
capture, indicating very strongly there are other means of detecting 
moving objects than those provided by a simple or compound 
eye. If we now examine the hairs on the larva we find different 
forms (C), spreading out almost the shape of a palm leaf on a 
slender shaft. Another (E) is very curious in its formation, having 
