192 [August, 



28. HYDROPlIOliUS Whlbg. 



1 (10) Wings quite unspotted. 



2 (3) Scutellum with only two bristles \. bisetusljyf. 



3 (2) Scutellum with four bristles. 



4 (5) Face brilliant brassj on upper half 2. balticus M.sig. 



5 (4) Face all whitish or orange. 



6 (9) Face all whitish. 



7 (8) Jowls obvious ..'. ^. prsecox liehm. 



8 (7) Jowls absent 4. litoreus Fall. 



9 (6) Face all orange 5. viridis Meig. 



10 (1) Wings with at least a dark spot on last piece of discal vein. 



11 (16) Wings with two rather faint dark spots. 



12 (13) Face burnished blue-green on upper half 6. bipunctatus Lehm. . 



13 (12) Face nearly all whitish or orange. 



14 (15) Face ( (J ) silvery whitish 7. borealis Lvr. 



15 (14) Face orange 8. rvjibarbis Gerst. 



16 (11) Wings with numerous spots 9. nebulosusFa.il. 



1. II. hisetus Lw. : apparently very common ou all the coast of 



Britain, at any rate I have taken it at a great many locali- 

 ties, of which all except Coniston (where I have taken 

 several marine species) were on the sea-coast ; the most 

 divergent localities were Exmouth, Dyffryn, Aldeburgh, and 

 Grolspie. Although this species has been well known in 

 Britain for more than fifty years it has not yet been 

 recorded from the Continent. A female taken at Dyffryn 

 on July 21st, 1888, has a small extra bristle on the 

 scutellum. 



2. H. balticus Meig. : not uncommon from Cornwall to Nairn, 



preferring the coast. 



3. H. prcBcox Lehm. : in various localities, from Cornwall to Suther- 



land ; also occurring ou the sea-coast, but not at all un- 

 common on pools inland. A number occurred recently on a 

 newly-made pond in my garden, but most likely they arrived 

 as larvse in some Wicken Fen earth which had been placed 

 in the pond. 



4. R. litoreus Fall. : I have taken this in Sussex, Middlesex, Suffolk, 



and Norfolk, but in spite of its name never on the coast. 



5. H. viridis Meig. : 1 took one female of this species at Hendon on 



November 9th, 1867, and one male at Ormesby on June 22nd, 

 1881. 



6. R. bipunctatus Lehm. : from Cornwall (Helston) to Inverness 



