Insects. 5177 



On looking down the insect, in clean specimens, there usually appears 

 a distinct black sinuated band at the base of the elytra and thorax, 

 not distinct in ruficollis. Fermaire says that fluviatilis is rather the 

 largest. Both insects vary a good deal in size, and when taken in 

 series appear to me of much about the same magnitude, but fluviatilis, 

 being narrower, looks perhaps relatively longer. Lastly, every spe- 

 cimen I ever took has been in running water, often in company with 

 ruficollis, but I have never taken it in pits, in which that insect 

 abounds. These differences may be sometimes individually slight, 

 yet one cannot mistake the tout ensemble of two clean series compared 

 with each other. I have only taken it at Cowley and Bradgate. Mr. 

 Bold takes it in Northumberland. I suspect it is rather undistin- 

 guished than rare. 



9. H. obliquus, Fab. 



10. H. confinis, Steph. = lineatus, Aube. 



These are at once distinguished from every other species by the ab- 

 sence of deeply punctate striae. H. obliquus is tolerably constant in 

 its pale cinereous colour, with broad black interrupted lines, more or 

 less confluent: confinis is readily distinguished from it by having tho- 

 racic furrows, which obliquus has not ; it varies much in colour, from 

 pale cinereous to ferruginous. In one form the dark lines are more 

 continuous, but not confluent : in another, a pale northern variety, 

 they are much interrupted and abbreviated. H. obliquus is generally 

 distributed, confinis not so common. I have taken it at Wandsworth, 

 Cambridge, Woking, Notting Hill, Rothsey in Northumberland, but 

 sparingly. 



11. H. lineatocollis, Marsh, cannot be mistaken. It has a flat, oval, 

 boat-shaped form, little attenuated behind : colour cinereous : thorax 

 with a long curved dark furrow on either side, and a more or less dis- 

 tinct dark mesial line. Common everywhere. 



I have stated that several of the more uncommon species may be 

 obtained at Cowley, about a mile from West Drayton- It is one of 

 my favourite localities for water-insects. Some pits and a stream 

 there have afforded me, amongst others, Hydroporus decoratus, vittula, 

 nigrita, Fab., angustatus and memnonius, a fine series of Octhebius 

 aeneus, O. margipallens, Haliplus elevatus, affinis and fluviatilis, Ily- 

 bius angustior and Orectochilus villosus ; also many good Brachely- 

 tra, as Siagonium quadricorne, Homalota cuspidata, deplanata, &c, 

 and many Pselaphidae. 



The neighbouring locality of Black Park, well known to Lepi- 

 dopterists, is also worthy the attention of Coleopterists. I took there 

 XTV. 2 k 



