294 
NOimi AMERICAN GYRINUS (cOLEOPTERa) 
the elytra are covered with very distinct transversely obliiiue 
sti'iolae but without reticulation, which perfectly defines the 
species we are considering. As for Aube’s statement, we have 
no known sjiecies of Gyrinus with reticulate males and smooth 
females, and are forced to conclude that either his male was 
abnormal or his supposed sexes were of different sjiecies. Reg- 
imbart’s characterization of affinis does not at all agree with 
Aube’s as to surface sculpture, and as he seems in no instance 
to have' seen Aube’s types, it is likely that his ajfini.s is not that 
of Aube. The matter is thus somewhat involved, and it looks 
as though actual study of tyjies will be needed to straighten it 
out. Aleanwhile 1 think it best to folloM^ LeConte in using 
the name affinis for our species with the fine oblique striolation, 
a character which distinguishes it from every other species of 
oui‘ fauna. In size, affinis is only equalled or exceeded by 
pleuralis and the rare impressicollis. The color of the e])i- 
pleura is typically rufous, but specimens often occur Avith the 
coloi- so obscure as to seem black at first glance. 
2 1 . Gyrinus pectoralis LeConte 
'I'liLs species is at once sejiaralile from all others of our fauna hj' the an- 
l,(a'ior margin of the metasternum being emarginate and impressed each 
side, giving a trilobed outline. The si)ecies has no other salient characters. 
It is of average size, l)roadish oval form and moderate convexity; black, 
margins usually narrowly and feebly bronzed, but often not at all so; surface 
I)olished and without definable alutaeeous sculpture in either sex, but with 
numerous very minute dispersed punctures; strial punctures moderate, not or 
scarcely larger in the outer rows. Beneath, metallic black, the anal .segment 
concolorous or at most slightly brownish; legs dull rufous, the i)osterior 
thighs often slightly dusky. 
Male (jrnildlia . — Brownish piceous, paler basaUy; middle lobe gradually 
narrowed, about half as wide as the lateral lobes at a distance from the tip 
e<iual to the width of the latter, obtusely carinate above apieally, the tip 
narrowly rounded. 
Lexyth, 4.;j to .').() mm.; width, 2.4 to .4 mm. The lower limit is that of an 
exceptionally small example, t he great er nnmber of specimens being T) mm., 
or a littl(! mor(! in length. , 
Type locality. - -\Aik(' Siqxu'ior. LcC’oidi', also gives Hudson 
bay l•(‘gion. 
44ie sp('ci('s is sli iclly a iiorlln'i'ii oiu'; if is known lo mo fioin 
.Maniloba, (W'iiinipeg; ()nali; l’i(pdl('nay Hiv('i'; Mil(' 2r)(t, 
