902 THE ENTOMOLOGIST. 



Cnemidotus impressus, the first of the "water beetles in the 

 British list, is found in stagnant waters near Putney and Wands- 

 worth. Pelobius Hermanni, Hydrophilus piceus. Hydrous cara- 

 boides, and Dytiscus circumfiexus are also insects that particularly 

 affect the London district ; the first three are much sought after 

 for the aquarium, and used to be collected and brought to Covent 

 Garden for sale for this purpose. The Hydropori are a very 

 large, and in many cases a very obscure group ; the brighter 

 coloured species, such as H. 12 -jyustidatus, H. depressiis, H. 

 assimilis, H. fluviatilis, H. septentrmiaUs, H. pictus and others, 

 are usually found in running streams, accompanied by Brychius 

 elevatns, and also Haliplus ohliquus, which latter insect, however, 

 seems to be found in both running and stagnant water. The 

 Hydropori that frequent the deeper parts of running streams are 

 usually found attached to logs or stones, and sometimes may be 

 found abundantly under stones at the bottom, after the fashion of 

 the Ebnides. Hydroporus latus is found in lakes among stones in 

 the same way, and this perhaps explains its rarity. Hydroporus 

 minutissimus is only found on the edges of the large fresh- water 

 basin close to the sea at Slapton Ley, in Devonshire, where it 

 was discovered by Mr. Wollaston, and with it Limnius troglodytes, 

 which latter beetle, however, has been found elsewhere in numbers 

 by Dr. Power. 



The smaller Hydropori, such as H. atriceps, H. umbrosus, H. 

 tristis, H. obscurus, and others, are very obscure; the majority 

 of them may be found in Askham Bog, near York ; of these and 

 the other Askham Bog beetles I have lately given a full account 

 in the ' Entomologist's Monthly Magazine ' (vol. xviii. pp. 7 — 9 ; 

 June, 1881), and need not again enumerate them. Some of the 

 Hydropori, such as H. lituratus, H. memnonius, and sometimes 

 H. tristis, seem especially to prefer small ponds in woods, while 

 others are fond of brackish water, such as H. confluens, which I 

 have found in abundance in pools at Hunstanton, within a few 

 yards of high-water mark; others again are quite indifferent. 

 I have found H. lepidus in profusion in a stream near Bourne- 

 mouth, quite close upon the sand, and also in a pond in a wood 

 near Lincoln. 



The species of the genera Noterus, Laccophilus, Colymbetes, 

 and Ilyb'ms, with very few exceptions, are all common in stag- 

 nant waters all over the country. With regard to the Agabi, A. 



