. Classification of the Coleoptera of North America [microform]. Beetles; Beetles; Coléoptères; Coléoptères. 138 COLEOPTERA OF NORTH AMERICA. are distinguished from all other groups having the anterior coxaj prominent and the side pieces of the metathorax narrow, by the sixth ventral segment not being visible; the fifth and propygidium are closely connate, with the suture indistinct, and the spiracle is placed midway between the anterior and posterior margins; the ventral sutures are distinct in all of our genera, and the apical margin of the thorax is membranous, except in Alobus; the antenna
. Classification of the Coleoptera of North America [microform]. Beetles; Beetles; Coléoptères; Coléoptères. 138 COLEOPTERA OF NORTH AMERICA. are distinguished from all other groups having the anterior coxaj prominent and the side pieces of the metathorax narrow, by the sixth ventral segment not being visible; the fifth and propygidium are closely connate, with the suture indistinct, and the spiracle is placed midway between the anterior and posterior margins; the ventral sutures are distinct in all of our genera, and the apical margin of the thorax is membranous, except in Alobus; the antennai are 10-jointed, except in Diazus. Anterior claws with a slightly proniiueut tooth near the tip; midillu and posterior claws cleft. Orsosyx. Claws alike on all the feet; Last joint of maxillary palpi oval, somewhat pointed; Anteiniie 9-jointed ; claws entire. DiAzus. Antennie 10-jointeil; claws cleft or toothed. Diplotaxis. Last joint of maxillary palpi elongate, cylindrical; claws with a very large tooth. Alobus. Sub-Tribe 7.—Melolonthini (genuini). This is the first of the sub-tribes in which the anterior coxa? are not prominent, but simply transverse, and contained entirely in the coxal cavities. It is distinguished from the other sub-tril>es having this character, by the labrum being deeply emurginate, and the ventral segments connate, though the sutures are frequently not eft'aced. The apical margin of the thorax is never membranous; the fifth ventral segment is connate with the ijropygidium by an angu- lated suture, sometimes partly obliterated; tiie spiracle is placed at the angle of this suture, nearer the posterior than the anterior margin. The genera indicate three groups, distinguished as follows:— Side pieces of metathorax narrow; Labial palpi on tlie under surface of the ligula. Riiizotrogi. Labial palpi at the sides of the ligula. TosiKcoprEii^. Side pieces of metathorax wide. Melolontu^i;.. Group L—Rhlzotroji, This group is sufficiently distinguishe
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