Whilst on the one hand Elmis makes an approach to the 
Parnidae, it appears on the other to be allied to the Helopho- 
ridae ; nevertheless the trophi and antennae are so very dif- 
ferent from both, that it does not seem possible to include our 
genus with either, for which reason I have proposed the family 
Elmidae. Panzer called the type a Dytiscus, from its inhabit- 
ing the water ; and Marsham, viewing its straight antennae and 
margined thorax, placed it with the Chrysomelae. Latreille 
first considered it to connect Hister and Heterocerus, but sub- 
sequently arranged it more naturally between the Parnidae and 
Hydrophilidse. 
The following species are British. 
1. E. Volckmari Panz. — Curtis Brit. Bnt.pl. 294. 
May, June and August : at roots of grass on the banks, 
also under stones in the beds of rivers and brooks ; 
near Hebden-bridge, Yorkshire, Hatfield and Bris- 
tol. 
2. E. tuberculatus Mill. — lineatus Kirby. 
At Clengre, Gloucestershire ; also in Norfolk, Suffolk, 
and near Hull, Yorkshire. 
3. E. variabilis Leach.- — Steph. pi. 13. f 4. 
Hebden-bridge, and near Carlisle; Netley, Shrop- 
shire, and Spitchwick, Devon. 
4. E. lacustris Spence. — Steph. — stagnalis Kirby ? 
Near Hull, and under stones in the river at Costessey, 
Norfolk. 
5. E. fluviatilis Steph. — Troglodytes Gyl. P 
Said to have been found in Norfolk. 
6. E. parallelipipedus Mill. — Steph.pl. 13. f 5. 
In a brook near Hebden-bridge, and supposed to have 
been found near Exeter. 
7. E. aeneus Mill. — Megerlei III. — Maugetii Lat. 
This is found from June to September, distributed over 
the kingdom, and is much attached to the leaves of 
Menyanthes trifoliata . 
8. E. obscurus Mill. ? — Maugetii Steph. 
Probably a variety only of the last. 
9. E. cupreus Mill. — Steph. pi. 1 3.f 6. 
Under stones in the outlet at Costessey Mill, Norfolk ; 
also in June near Hatfield; and I am indebted to 
Miss E. Hill, of Pilton, Devon, for specimens from 
the river Avon. Mr. Hobson and Mr. Smith hav- 
ing presented me with several of the species, the 
5th is the only one I do not possess. 
Some of these insects being found upon the leaves of the 
Menyanthes trifoliata (Marsh Trefoil or Bogbean), this beau- 
tiful plant is represented in the plate. 
