Insects. 4923 



that this character is one of the best to facilitate a correct separation 

 of the species. 



17. D. dimidiatus, III., Curt. Brit. Ent. pi. 99. This, which is 

 the largest British species, has been taken principally at Whittlesea 

 Mere, with D. angustatus, in ditches, in May, June and July. 



18. D. flavoscutellatus, Lat. f was, by an error, printed " flavo- 

 maculatus" in the ' British Entomology:' it is the D. circumflexus 

 of Illiger, and the D. excrucians of Stephens in the * Zoological 

 Journal.' 



Cybister, Curtis. 



19. C. Roeselii, Fab., Curt. Brit. Ent. pi. 151. The female 

 figured by me was found on the 30th of September, 1826, in a 

 puddle at Walton, Essex, by J. Dane, Esq., and is in the cabinet ol 

 Mr. J. H. Griesbach. Another specimen was obtained by Mr. Davis, 

 in August, 1831, which had been thrown out of an oyster-basket in 

 the City Road, and the beautiful female in my own collection was 

 taken out of a pond with other Dytisci on the 12th of September, 1836, 

 at Southchurch, Essex, and presented to me by Mr. C. Parsons, 

 F.L.S. 



Acilius, I^ach. 



20. A. caliginosus, Curt. Brit. Ent. pi. 63. This has been decided 

 to be the D. fasciatus of Degeer, since T published the genus in 1825; 

 it was discovered the previous year at Whittlesea Mere, by Mr. Chant 

 in July. 



The variety of A. sulcatus which I named A. scoticus was captured 

 at Kinnordy, in Forfarshire, and presented to me by Sir Charles 

 Lyell. 



It is a curious fact that these water-beetles fly by day, when it is 

 fine : an Acilius alighted on a carriage in which I was riding, near 

 Heron Court, on the 15th of September, in the middle of the day, as 

 we were driving towards Bourne-mouth, and at the same time a 

 Colymbetes flew down. 



In conclusion, I hope that other entomologists will assist in 

 advancing our knowledge of this interesting tribe, by contributing 

 such information as they may possess, and especially the localities 

 and dates of capture of the rarer species. 



John Curtis. 



Belitha Villas, Bavnsbury Park, 

 October 18, 1855. 



