1890 Insects. 



Genus Hydroporus, Clairville. 



1. H. incequalis, Fabr., Gyll., Steph., Erichs., Aube, &c. 

 Dy. parvulus, Fabr. 



— trifidus, Marsh. 

 Hygrotus reticulatus, Steph., not Fabr., &c. 



2. H. reticulatus, Fabr., Gyll., Erichs., Aube, &c. 

 Hygrotus collaris, Panz., Steph. 



Var. Hy. affinis, Steph. 111. 



3. H. decoratus, Gyll., Sturm., Erichs., Aube. 

 Hygrotus decoratus, Curtis, Steph. 



4. H.pictus, Fabr., Gyll., Steph., Aube, &c. 



— arcuatus, Fabr., Panz. 



5. H. lepidus, Oliv., Schonh., Aube. 

 Hygrotus scitulus, Steph. 



6. H. confluens, Fabr., Panz., Gyll., Steph., Aube. 



7. H. rivalis, Gyll., Aube. 

 Hygrotus fluviatilis, Steph. 

 Hy. Stephensii, Rudd, Steph. 



I am not perfectly satisfied that this species is really different from the following. 

 The only distinguishing character is the maculation of the elytra ; and from the iso- 

 lated or more or less confluent black lines of the H. Sanmarkii, there appears to exist 

 every link to the irregular black patches of H. rivalis. 



8. H. Sanmarkii, Sahib. 



— assimilis, Gyll., Aube, Steph., not Payk. 



9. H. septentrionalis, Gyll., Aube. 



— alpinus, Kunze, Steph., not Payk., Gyll. 



— fluviatilis, Sturm. 



The true H. alpinus, Payk., Gyll., of which H. bidentatus, Gyll., Aube, is the fe- 

 male, and H. borealis, Gyll., a variety, has hitherto not been found in Great Britain. 



10. H. Davisii, Curtis, Steph., Aube. 



— borealis, Steph., Aube, not Gyll. 



— alpinus, Duftschm. 



— septentrionalis, Heer. 



11. H. assimilis, Payk., Sturm. 



— frater, Kunze, Steph., Aube. 



— halensis, Steph. Man., not Fabr., Erichs., Aube. 



— areolatus, Steph. 111. 



— affinis, Sturm. 



12. H. halensis, Fabr., Germ., Erichs., Aube. 



— areolatus, Duftschm. 



— griseo-striatus, Steph., not Degeer, Gyll., Aube. 



Of this species I have seen one British specimen only, existing in Mr. Stephens's 

 collection. 



13. H. elegans, Hlig., Panz., Sturm. 



— brevis, Sturm. 



— depressus, Steph., Aube. 



