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THE ENTOMOLOGIST. 



far as I am at present able to judge, the result in the Coleoptera 

 will be very much the same. 



As observable in dried specimens, the oedeagus of Gyrinus is 

 a corneous body consisting of a median and a pair of lateral 

 lobes, found between the dorsal and ventral surfaces of the last 

 abdominal segment; for a short distance from its base it is 

 somewhat oval in section and parallel to the long axis of the 

 body, -but its parts are abruptly and obliquely bent upwards to 

 follow the curve of the last ventral segment. The side lobes, the 

 form of which does not vary in any marked degree in the 'several 

 species, have the basal half of their inner faces excavated for 

 the reception of tbe basal half of the median lobe ; their apical 

 half is flattened and blade -like, and their apices are fringed with 

 long cilia. The form of the median lobe is various, and peculiar 

 to the respective species ; its contour in some of our species may 

 be gathered from the outline figures. The latter are made from 

 specimens in Canada balsam, and magnified 4.0 diameters ; but in 

 the Table of Species I have described its appearance when merely 

 dissected out and viewed from above with a hand-lens magnifying 

 about 20 diameters. 



1, (Edeagus of Gyrinus ehngatus. 2, Median lobe of cedeagus, G. opacus , 

 3, of G. marinus ; 4, of G. bicolor. 



As it became necessary, in the preparation of this paper, to 

 re-examine the British species of Gyrinus, I have thought it well 

 to include some general observations, with a Table of our species 

 to facilitate their determination. 



It is evident that we have in Britain two kinds of Gyrinus 

 with the reflexed margins of the thorax and elytra testaceous 

 and the interstices of the latter sculptured ; in one of these (a) 



