July, 18CG.] 25 
ABOUT AQUATIC HEMIPr£?R.4 ; INCLUDING NOTICES OF NEW BRITISH 
SPECIES, &c. 
BY J. W. DOUGLAS. 
The following Lave been recently taken, mostly in the spi'ing, in the 
localities named. 
Hydrometra pallidum. Fab. — About a dozen on an isolated pond at 
Caterham, and a single one at Eltham. This, one of the largest 
species, also remains one of the scarcest. 
E-ydrometra odontogaster, Zett. — This species, new to our lists, has been 
taken at G-ravesend, Lee, and Esher. It is smaller than H. lacus- 
tris, which it most resembles, but the abtlomen is black beneath ; 
in the ^ the last abdominal segment, on the under-side, is furnished 
with two short, black, downwardly and for wardly projecting spines, 
and in the ? the first genital segment has a deep transverse furrow. 
These characters are best seen, in both sexes, by a transverse view, 
and by them the species is easily distinguished from all others. 
Hydrometra aryentata, Schum. — Mr. Scott and I were fortunate enough 
to take several of this, the smallest European species, on a pond at 
Esher, through which a stream runs. The characteristic silvery 
scales on the hinder margin of the pronotum, conspicuous enough 
in life, for the most part got removed by abrasion in the collecting 
bottle. This may account for the want of any mention of them 
by Curtis in his description, or of representation in his figure of 
his H. apiealis, which is, nevertheless, identical with argentata. 
Mr. Dale, who furnished Mr. Curtis with the example he described 
and figured, had also the kindness to give me one, taken at the 
same time and place, in which a trace of the w^hite scales still 
exists. 
Hydrometra Costce, H. Schf. — Mr. McLachlan took a single specimen 
in Perthshire in June last, which I believe to be this species, new 
to us, but I should like to see more examples and some of each 
sex. I should therefore be greatly obliged if any collector in 
Scotland this summer would capture and send to me any Hydro- 
metrcB he may see, in the hope that this fine species may be among 
them. It is rather larger than H. thoracica, is broadly red on the 
middle of the pronotum, and is especially wide across the region 
of the middle coxae. 
Banatra linearis, Lin.— In clay pits at Lee, and the pupa, covered with 
mud, in a pond at Esher ; so it would seem that the winter is 
passed by the insecta while in an imperfect state. 
