38 [ FEBRUARY, 
b. Antenne in frontem inserte. 
Scrobiculi antennales medii, laterales, prosterno subpro- 
ducto i 4 ; alia aie : N ; - Teretrivus Er. 
Scrobiculi antennales ad prosterni latera siti . 3 - Pxiecaperus Er. 
Scrobiculi antennales antici : “ - Onruopnuitus Leach. 
Scrobiculi antennales medii, laterales, prosterno truncato Asraus Leach. 
Hister Linné. 
I have included in this genus Omalodes and Platysoma; as they are founded 
on slight differences in the form of the tibiz. Plasius and Placodes will also 
probably enter here; at least I cannot find anything to separate them, except 
differences in the spines of the posterior tibiz. 
The posterior tibia of this genus, are generally broad, and externally armed 
with two series of spines: sometimes a range of bristles on the posterior face of 
the tibize is enlarged so as to simulate a third row of spines; sometimes (Hister 
arcuatus Say) the whole outer surface of the tibie# is rough with confused spines; 
in H. costatus (n. sp.) the posterior tibia are narrow, and the spines are very 
fine: these tibiz are usually not toothed on the outer margin, yet in H. sexstri- 
atus Lec. they are distinctly four-toothed: they are also toothed in the species 
referred to Omalodes and Platysoma, the number of teeth in the latter being 
variable, and the teeth themselves frequently indistinct: they are entirely smooth 
in some small species allied to H. subrotundus, and belonging to Erichson’s 3d 
division; the posterior feet are smooth, and the intermediate ones armed with a 
single tooth near the apex in H. corticalis Lec.; finally, the posterior tibiz are 
broad, very much compressed and finely serrate in Omalodes Harrisii Lec. 
The anterior tibiz are broad, compressed and more or less distinctly toothed 
on the outer margin, usually with a single row of very short articulated spines; 
on the anterior face is a groove for the reception of the tarsus; the inner margin 
of this groove is sharply defined; the outer margin indistinct, in most species ; 
more distinct in the species referred to Omalodes; some of the species of Platy- 
soma have the outer margin distinct, while in others (H. Carolinus Payk.) it is 
quite indistinct. The species, with the exception of the large tropical species, 
which would probably form a separate division, can be arranged according to 
the following table; the internal marginal stria of the thorax, when it exists, is 
entire, and extends around the whole apex of the thorax; the outer stria always 
ends at the anterior angle. 
A. Thorax stria marginali interiore integerrima, antice ambiente. 
* Thorax stria marginali margini valde approximata. 
Thorax stria marginali unica; (tibiz posteriores dentate.) Omalodes Er. 1 
Thorax striis marginalibus duabus ; (tibia post valde compress serrulate.) 2. 
** Thorax stria marginali interiore a margine remota. 
a. Thorax margine ciliato; (scrobiculi antennales non profundi.) - 
Tibiz posteriores dilatata ° : ° . ° : ° ° 
Tibie posteriores tenues. ; j ° . ° ‘ ‘ >) Abe 
b. Thorax margine glabro; (scrobiculi antennales profundi.) 
a. Tibie posteriores subdentate : : ; ° 4 5 satis 
b. Tibie posteriores biseriatim spinulosie. 
+ Mesosternum emarginatum. 
a. Epipleure excavate unistriate: (tibi# antice multidentatx) - 16; 
4. Epipleure non excavate, pluristriate. 
Tibiz antice parce dentate, epipleure bistriatz ° : : a to 
Tibi antice parce dentate, epipleure tristriate 4 5 : 5 tb 
Tibiz antic serrulate vel mutice, epipleure bistriate ° : 5) Gh 
tt Mesosternum truncatum. 
Epipleure bistriate  . ° 5 ° 6 : : : “ - 10. 
5 11. 
Epipleure angustissime, unistriate . .. 
