125 



Philydrida, MacLeay. 

 Hydrophilid^e, Leach. 

 Hydrophiloidea, Hope. 



Genera. 



Country. 



Typical Species. 



1. 



Hydrous, Linneus 



England 



D. Piceus, Linneus. 



2. 



fHydrocharis, Lat. 



\ Hydrophilus of Authors 



England 



D. Caraboides, Linn. 









3. 



Philhydrus, Solier 



Europe 



Hyd. bicolor, Fab. 



4. 



Hydrobius, Leach 



England 



Hyd. fuscipes, Linneus. 



5. 



Tropisternus, Solier 



Mexico 



Hyd. lateralis, Fab. 



6. 



Stemolophus, Solier 



Egypt 



Hyd. Ruflpes, Solier. 



7. 



Volvulus, Brulle 



Mauritius 



Hyd. inflatus, Brulle. 



8. 



Berosus, Leach 



England 



Dyt. luridus, Linneus. 



9 



Enoplurus, Hope 



East Indies 



Ber. Orientalis, Hope- 



10 



Spercheus, Fabricius 



England 



Hyd. emarginatus, Fab. 



11 



Limnebius, Leach 



England 



Hyd. truncatellus, Fab. 



12 



i Chsetartliria, Water. 

 f Cyllidium, Erichson 



England 



Hyd. Seminulum, Paykull. 









1. Hydrous, Linneus. 



The species of this genus are much more nume- 

 rous than Entomologists are aware of, and from the 

 notes contained in my Journal I find, at least, 

 seventy species have fallen under my notice ; they 

 seem to be naturally divisible into three sub-genera, 

 1st. into true Hydrous, which has the wings 

 rounded at the apex and spineless. 2nd. Those 

 species which have the sutural apex of the elytra 

 more or less spined, to which I give the name of 



