II FLIES WITH AQUATIC LARV^ 155 



ease. Meinert, who has given the best account of 

 the larva and pupa of Tanypus, says that the suckers 

 are circular depressions outside the dorsal shields of 

 the abdomen. The pupa of Tanypus varius shows 

 them most distinctly : here they are borne in pairs by 

 four segments (3-6). When the pupa has attached 

 itself by a single sucker, it can turn about without 

 losing its hold.^ 



The eggs of Tanypus are described by Hammond -^ 

 as circular gelatinous masses, adhering to floating 

 objects. The eggs are arranged in double rows, along 

 about eight straight and parallel lines which extend 

 across the disc. 



Ceratopogon. 



One of the commonest Dipterous larvae found at 

 the surface of ponds is the long slender worm-like 

 larva of Ceratopogon bicolor. It is commonly met 

 with entangled in the confervae which float at the 

 surface, and its extremely slender body seems well 

 adapted for travelling in a serpentine way through 

 a mass of vegetable threads. The head is very long 

 and slender ; there are no limbs. At the tail-end 

 is a crown of long bristles, which can either be ex- 

 tended backwards or curved forwards at pleasure. 

 These bristles are probably a means of attachment 

 and locomiotion. The surface of the body is marked 

 with fine longitudinal lines, which look as if they 

 had been cut upon the cuticle by a microscopic 



1 De eucephale Myggelanier^ p. 83. 

 - Postal Microscopical Journal. 



