A GUIDE TO THE STUDY OF BRITISH WATERBUGS. Ill 



remarkable. According to Douglas and Scott, the mesonotum 

 comprehends the two basally-rounded plates posterior to the 

 pronotum, but this view has not apparently been confirmed by 

 other authors. In my own collection I possess apterous forms 

 only, and have examined but a single macropterous individual (of 

 the specific identity of which I am not certain), so that I cannot 

 add anything as yet to our knowledge of this genus. Detailed 

 descriptions will be found in the 'Ent. Mo. Mag.,' iv., 1867, 

 p. 5, Plate i., fig. 1 (brachypterous), and in Saunders's ' Hetero- 

 ptera,' p. 146 (brachypterous form figured in the large edition, 

 Plate xiii., fig. 7). The apterous form, which has not to my 

 knowledge been previously delineated, appears on Plate i., fig. 6, 

 where the $ is figured ; the ? is a little broader, and differs in 

 the structure of the genital segments. Mesovelia furcata has 

 been recorded from Burton-on-Trent, Woking Canal, and near 

 Windsor. I have twice searched for it at Woking, but without 

 success ; this may be due to the fact that the canal has been 

 cleaned out somewhat frequently of late years. 



Some interesting observations by E. A. Butler were published 

 in the 'Ent. Mo. Mag.,' 1893, xxix., pp. 232-6. The insects 

 were found on a pond near Windsor, on the leaves of Potamogeton 

 nutans, from which, however, they were with difficulty distin- 

 guished. They are carnivorous, according to Butler, feeding 

 upon Smynthuvus and other small insects. 



Hydrometra* ( = Limnobates) is yet another genus of doubt- 

 ful position, containing one species — H. stag novum (Linn.), upon 

 which the following specific names have also been inflicted at 

 various times, viz. : acus, alata, angusta, angustata, lineola, and 

 pallipes ! As it cannot be mistaken for any other British water- 

 bug, it will not be necessary to linger here upon its structural 

 peculiarities. It is described and figured in Douglas and Scott 

 (Plate xix., fig. 7), in Saunders, and also in Miall (fig. 102), and 

 is, moreover, beautifully figured in Curtis's 'British Entomology.' 

 Mr. Saunders has kindly called my attention to a mistake in a 

 former part of this " Guide " (Entom., 1899, p. 6), where I wrote : 

 " in all the aquatic forms .... the anterior legs are raptorial. 

 In all the femora are dilated." The present genus had escaped 

 my memory, as, of course, the anterior legs are very slender and 

 very similar to the other two pairs. Although doubtless they 

 are employed for holding the food during feeding, they cannot be 

 said to be noticeably modified for raptorial purposes. Hydvo- 

 metva is a very timid bug, keeping close to the banks of the 

 stream or ditch which it frequents, and moves with a slow, care- 

 ful, almost pensive tread, very distinct from the jerky sprawl of 

 Gevvis ; it is moreover not so gregarious as are most of the other 

 semi-aquatic species. 



* v$ap (Jiudor), water; pt-TPciv (metron), measux*e. 



