198 SHARP: HYDRADEPHAGA OF LANCASHIRE AND CHESHIRE. 
Fialiplus has eleven recognised British species; two of them 
H, rujficollis and H. lineatocollis, are two of our most abundant wate 
beetles, and I have, I think, never dragged pond or ditch in the 
district without meeting with the former insect at any rate. 
HZ. obliquus I have only taken in Flintshire, but Dr. Ellis has it ‘rot 
Bidston near Birkenhead. 
H. confinis is a scarce insect. I have never taken it in Cheshire,, 
but Mr. Kinder reports it from Kirkdale. 
Hf, fulous and Hi. flavicollis are fairly common. 
HZ. fluviatilis has been recorded, and Dr. Ellis has taken Z. striatus, 
which seems more probably to be only a racial variety of A. rujicollis, 
and not a distinct species. Thus of the eleven species of this genus 
we have records of eight ; the other three are rare everywhere. 
f the PELoBIIDA there is but one genus, Pe/obius (dweller in 
the deep), and one species, which is very uncommon in the north 
but has been taken at least once by Mr. Gregson at Rufford. 
The next family, Dyriscip#, contains a number of genera, which 
have been arranged under various tribes and sub-families, with which, 
however, we need not concern ourselves here, as it will be less con- 
fusing to treat of the genera simply as they are placed, but the groups 
in which they are massed in the table will give some idea of their 
affinities. 
Noterus (the wet one) is a small genus of two species. One of 
these, WV. sparsus, occurs in the district, but not by any means 
frequently. 
Then comes Laccophilus (lake lover). There are three species. 
Their synonymy is rather confusing, and Canon Fowler has altered 
the specific names of the first two. Good and sufficient reasons 
doubtless exist for his doing so, but it is nevertheless very confusing, 
after having learned to recognise certain forms by certain specific 
names, to be suddenly called upon to change or even reverse them. 
The first of these species of Laccophilus, L. minutus, I have never | 
been able to discover in the district, but it has been reported by 
Dr. Ellis. The second, now called Z. Ayadinus, I have taken quite 
abundantly in most of the Cheshire ponds. It was particularly 
plentiful in 1890; the previous year I had not taken more than two 
or three. In this connection I may observe that I haye noticed that 
every year seems to have its particular water-beetles, which then do 
more especially abound, and then seem to die out perhaps for years- 
The laws which govern these phenomena are exceedingly obscure, 
but it is impossible to doubt that they are controlled by laws pet- 
fectly rigid in their application. I am m yself persuaded that such 
instances are similar in character to the Gace abundance of such 
Naturalist, 
