JOURNAL 
OF THE 
ROYAL MICROSCOPICAL SOCIETY. 
DECEMBER, 1922. 
TRANSACTIONS OF THE SOCIETY . 
xv._ LARVA OF CHAOBORUS CRYSTALLINUS 
(DE GEER) (CORETHRA PLUMICORNIS E.). 
By Sydney Charles Akehurst, F.R.M.S. 
( Read October 18, 1922.) 
Four Plates and Fifteen Text-Figures. 
The larva of Corethra plumicornis has been of considerable interest 
to microscopists for the last sixty years, partly because of its 
transparency, also on account of it being a highly organized 
aquatic species. (See PI. XVI., fig. 1.) 
The imago is incapable of biting man or animals, and plays no 
part in the transmission of disease. Probably on account of this 
Corethra has not received so much attention as members of the 
Culicidse. Most of the important papers in our own periodicals 
concerning this larva appear round the period of 1865-1867, with 
one or two further publications about thirty years later. 
Concerning the question of nomenclature, an interesting paper 
appeared in the Entomologist’ s Monthly Magazine, 3rd Series, 
vol. vi., by F. W. Edwards, from which we gather the following : — 
“ Corethrin^e. — The name of this sub-family has to be altered, 
since the generic name Corethra must give place to Chaoborus, 
which was established two years earlier. The latter name was 
founded on the larva only, but the rules of zoological nomencla- 
ture lay down the principle that such names are valid, and the 
rule of priority must be applied to them.” 
We now have Corethra plumicornis E. re-named Chaoborus 
crystallinus (de Geer), and the other British species as Chaoborus 
pallidus, but, as a matter of convenience, we have retained the 
more familiar names. 
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