BRITISH WATERBUGS. 79 



should be known by the apex of the clypeus being transverse, and 

 having two keels close to the base ; its base of thorax, too, appa- 

 rently is not angled laterally. 0. vernalis, Sauss., is an allied 

 species ; it has a tubercle on the second abdominal segment on 

 the back. Neither with O. vernalis nor with O. hizonatus does 

 Saussure make mention of the two deep furrows or depressions 

 on the apical half of the mesonotum. In my species they are 

 distinct in both sexes. 0. vernalis has an indistinct suture on 

 the first abdominal segment. The term " circular," used by 

 Saussure (Vespides, i. 148) to describe the clypeus of vernalis, is 

 certainly not applicable to the clypeus of my species in the 

 female, the only sex described of vernalis. 



A GUIDE TO THE STUDY OF BEITISH WATERBUGS 

 (AQUATIC HEMIPTERA OR RHYNCHOTA). 



By G. W. Kirkaldy. 



(Continued from p. 64.) 



17. A. GERMARi (Fieber). 18. A. carinata (C. R. Sahlberg). 

 I discussed these two fully in the * Entomologist ' for 1898 (xxxi. 

 249-51), and figured the palffi in the ' Quekett Journal.' In 

 translating Wallengren's Swedish in the former, however, I made 

 a bad mistake, to which Dr. Bergroth kindly called my attention. 

 " Hvarjamte uppehallsorten synes vara en annan " has no refer- 

 ence to the structure of the bug, but means " the habitat also 

 seems to be different," germari having been found in a small 

 lake with muddy bottom, far from the sea ; while carinata lives 

 in small pools on rocks at the seashore, and, in Lapland, on 

 Alpine rocks. 



CoRixA, Geoffroy. 

 (= Corisa, Amyot & Serville; Macrocorisa, Thomson.*) 



Of the general structure of Arctocorisa, but smooth and 

 polished, and the strigil is on the left side of the male. There 

 are two British species : — 



1. Prouotum with at least sixteen pale Hues . . fjcoffroiji. 

 la. Pronotum with not more than fourteen pale lines . affinis. 



1. C. GEOFFROYi, Leach. Generally distributed. The ova 

 are figured by Dufour and others ; they are subglobular, pointed 

 anteriorly. 



N.B. — The Scandinavian C. dentipes, Thomson, has been 

 confused with C. geoffroyi, but the intermediate tibiae are com- 

 pressly dentate at the base in both sexes. It may possibly be 

 found in Britain. 



'■' Greek koris, a bug ; Gi'eek inakros, big. 



