146 Mr. A. E. Eaton on some Species 
contained fluid into the intestine, over which ramify branches of 
the tracheal trunks. The distribution of these trachez varies, 
possibly according to the age of the imsect; yet the branches 
(in a Cloéon) which are given off from the trunks in the seventh 
and eighth segments (Dr. Schaum’s method of reckoning) are 
larger than those in the other segments, especially in young pupe. 
The genus Cloéon, as limited by M. Pictet, whom Dr. Hagen 
follows, may be at once divided into two groups, which in reality 
are genera, although not recognized as such hitherto. As it is 
therefore necessary to propose a name for one of them, I will 
suggest that Cloéopsis be given to C. diptera, L., on account of 
a variety of the male resembling in colour Cloé or Cloéon Rho- 
dant, Pict. 
CLozopsis, nov. gen. 
Comprises one widely distributed species, C. diptera, L. 
Gen. Cuar.—Pupa with six pairs of double branchial plates 
and one pair of single ones. Imago dipterous, with two aual 
setee, the third abortive. 
In this species the larger division of the double branchial plates 
of the pupa is nearly circular; the smaller is indicated by the 
dotted line in the figure. The single plates are also poe 
circular. It may perhaps be unnecessary to mention “| \ 
that, although Dr. Hagen has included it in his dia-  ~\.,5/ 
gnosis of the pupa, the possession of black wing- Outline of 
is indicati : : a double 
cases is indicative of state, and is not a special cha- _ branchial 
racter; in Cloéon Rhodani, and some other species pe: 
also, these organs become black shortiy before the final change 
of the pupa. Dr. Hagen, too, attaches great importance to the 
markings or absence of colour in the sete of the imago, as well 
as to the colour of the turban of the male. But there is scarcely 
any colour-character which, when fully tested, is not found to 
vary more or less in the species of this family. Specimens of 
this insect from Cambridge and Huntingdon often have the 
turban dull greenish yellow (like the legs of C. Rhodani subim.), 
instead of reddish brown (eyes of house-fly) ; and in the same 
localities the female generally has colourless wings, like the male. 
The sete are frequently not annulated. 
CLoion (as restricted). 
Gen. Cuar.—Pupa with seven pairs of single JEEP 
I P & des 
branchial plates. Imago with four wings and #7 | 
two anal sete; third seta abortive. See le 
plate of pupa(sp.?). 
In this genus the form of the rudimentary hind wings is very 
useful in determining the species, as it does not vary to any 
