Some species of this genus are oval, and others nearly globose ; 
the trophi also vary considerably, but the simple postpectus 
or sternum will distinguish the Hydrobii from Hydrophilus. 
They live in ditches, ponds, and stagnant waters, and are most 
abundant in April and May; but many, if not all of them, 
may be found during the whole year. The following are 
British species arranged according to their affinities. 
1. H. fuscipes Linn . — aquaticus Linn. — Scarabseoides Fab ., 
Panz . 67. 12. — Common everywhere. 
2. chalconotus Sam. — Curtis Brit. Ent. pi. 243. — Taken 
the middle of April in a pond near Lynn, Norfolk, 
by Mr. Davis, who presented me with specimens ; 
for others I am indebted to Mr. Stone, who took 
them in a pond of brackish water at Gravesend the 
end of August. 
3. substriatus Marsh. MSS. — This is probably only a dull 
pitchy variety of the last, and may be the H. picipes 
Fab. 
4. melanocephalus Fab., Oliv. 3. tab. 2. f. 12. a. b . — 
H. torquatus, dermestoides, and ochropterus Marsh. 
are varieties. 
5. bicolor PayJc ., Gyll. — lividus Lat. — fulvus Marsh. 
6. griseus 111 ., Fab. — bicolor Fab. — chrysomelinus Fab., 
Panz. 67. 15. — lividus Herb., Marsh., Oliv. 
7. margipallens ? Marsh. 
8. marginellus Fab. — affinis PayJc., Gyll. 
9. globulus PayJc., Gyll. — minutus Oliv. 3. tab . 2 .f. 13. 
1 0. foveolatus Have. Ent. Trans, p. 86. — June, near London. 
11. bipustulatus Marsh. 406. 13. 
12. Colon. From Mr. Blunt’s cabinet. 
13. minutus Linn., Gyll . — bipunctatus Fab., Oliv., Panz. 
67. 14. — Marsh. 
14. orbicularis Fab., Oliv., Panz. 67. 13. 
15. seneus Stev., Germ. — I have two specimens taken in or 
near the New Forest, Hants. 
16. Seminulum PayJc., Gyll. — nigrinus Marsh. 
I must not omit to observe, that Mr. A. Mathews detected 
several individuals of II. griseus carrying egg-pouches under 
their abdomens. 
The plant is Inula crithmoides (Samphire-leaved Fleabane), 
communicated by Mr. Gray, who found it in the Isle of 
Wight. I gathered it this year on the coast of Essex. 
