284 
NOIITII AMEIilt'AX GYRINUS (cOLEOPTERA) 
of like size, viz — latUinthus, rUchrous, aeneohis and ivoodnijjl. 
Of those, JaiiJi^nbuH may always be at once (listinjinislied l)y th (5 
(ransvers(' row of i)nnctures at tlie side of the thorax ])endinj>: 
iiKR-e stron<2;ly away from the front marj>;in, and by the more 
widely rcflexed side mar<2;ins of the thorax and elytra. Both 
IdtiJitNbus and dichrous have the eleventh stria evidently nearer 
the maro’in than in the other three species, and dichrous differs 
further in the darker colored ventral seg'inents. Aeneohis and 
u'oodniffi agree nearly with tnarginelhis in the very narrowly 
reflexed side margins of thorax and elytra, and in having the 
eleventh stria more distant from the margin. In aeneohis tlu; 
('idire ni)p('r surface is more or less distinctly bronzed. In 
iroodnijfi there is a faint aeneous luster in some examples at 
least, and in the female the surface gloss is slightly dimmed 
by a very fine alutaceous sculpture, not detectable' in niargin- 
elht.s. These two species, howevei-, may jn-ove difficult to dis- 
tinguish without reference to genitalic characters. 
S. Gyrinus dichrous LeConte 
Our smallest species with uoii-eariiiate scutellum, averaging hut little over 
4 mm. in length. Above black, sides narrowly and obscurely bronzed, snr- 
i'ace moderately shining, less highly polished than in many species but with- 
out definable alutaceous sculi)ture. Punctures of outer rows only slight!}' 
larger than those near the suture; eleventh stria rather close to the margin. 
Beneath rufous, with the ventral surface except the apical segment, dark 
brown or castaneons. 
Male (i(')ittali(i. — Rufo-testaceous, middle lobe slender ami parallel-siih'd in 
anical half, scarcely one-third as wide as the lateral lobes. 
LciKjtli, d.t) to 4.4 mm.; width, 2.2 to 2.4.a mm. 
Type locality. — “New England.” 
My s])('cim('ns ar(^ fi'om Maine (Alonmoufh — Ei'osf) ; Massa.- 
ehus('fls (d^yngsboro; Wak('field) : Nc'w York (C'luiumoul 
lMv(‘r — Nolimin): ('anada (Ottawa — B('aulne). 
'Die small size, d('ep black not v{'ry highly polislu'd surface, 
lulous umh'r body with dark('r veidi'al segnu'nfs, except Ihe 
l<‘rminal oiu', mak(' (his an ('asily r('(*ognizable s])ecies. b(' 
(’onte speaks in oiu' place' of this s])eci('s as being “scarcely 
bronz('d,” and in anolla'r as “not bronzi'd on llu' margin and 
sidure,” whiedi 1 l)('li('v(' to Ix' (lu' case' with llu' type'; but with 
ede'aii spe'edme'iis and the' preepe'r vie'w ])e)int the mai'gin will be 
