Objects for the Microscope. 129 



noonday on rose-trees and other shrubs. It is quickly 

 noticed from its long legs and metallic round-backed body, 

 carrying its head low, and sometimes found with another 

 fly in its mouth, being very predaceous. 



There are fourteen genera of the Dolichopidse, each con- 

 taining many species ; and some parts of their internal 

 anatomy present peculiarities so great that much has been 

 written about them by Latreille, Harris, Dufour, and others. 

 Their habit is to run along the surface of still water like 

 the Velia rivuhrum (see Velia), and they catch smaller flies, 

 aquatic worms, and even small gasteropods, the little Physa, 

 and smaller Planorbis ; there is a gaping orifice at the end 

 of the proboscis, which admits and holds the prey until the 

 juices are sucked out. 



We know not where they lay their eggs, but the larvae 

 are found as white slender worms of twelve segments in 

 May, underground in damp earth, and in June they change 

 to pupaB, casting their skin. The head of the pupa is armed 

 with several points, the ends of the legs in their sheaths, 

 somewhat detached from the body, and a process resembling 

 an S is on each side of the thorax, probably for respiration. 

 The Dolichopus emerges from the pupa in about three 

 weeks' time. Now let us examine the slide. 



The head is broad ; the eyes large, and in life were very 

 brilliant. The antenna? stand fiercely out and require 

 examination with the J-inch ; they are quite unlike any we 

 have yet seen. Observe three distinct joints besides the 

 arista or spine, which points forward ; the second joint, 

 the shortest, fringed with spines and intromitting a slender 

 tube obliquely into the base of the third ; you can see a 

 kind of loop or dark spot where it is inserted ; the third is 

 so remarkable that whenever you see this compressed and 

 peculiar shape you need not doubt that you have a Doli- 

 chopus. The arista is two-jointed, and in some species it 

 is ciliated. 



The proboscis is short, directed downwards ; the head 

 itself is armed with long bristles. The abdomen has five 

 segments, and on each of them you see a double row of 

 white spots, which are the spiracles; the end of the 



