EUCERA. 
233 
Halictus, Andrena, Dasypoda, Panurgus, Saropoda, 
Ceratina, Ccelioxys, Chelostoma, Heriades, Anthocopa, 
and Apathus ; of the second class we have Prosopis, 
Sphecodes, Macropis, Anthophora, Nomada, Melecta, 
perhaps Epeolus, according to Latreille^s idea, Stelis, 
Anthidium, Osmia, and Bombus; the third class com¬ 
prises in our series merely Cilissa, and in this series the 
male characteristics that have suggested the name are 
just as few, being limited to the present genus. But 
the males among the bees exhibit in many cases strong 
and striking peculiarities which distinguish them from 
their partners. Exclusively of the general distinction 
expressed in their organic difference by the possession 
of one additional joint to the antennae and one more 
segment to the abdomen than is exhibited in the fe¬ 
males, we find in many cases in these two parts of their 
structure verv marked singularities. Great sexual dif- 
ferences in the length of the antennae are not restricted 
to the present genus; in fact, in most of the genera, 
this is the first striking feature, but which becomes 
conspicuously so in some species of Sphecodes, in most 
of the Halicti, in some Noma dee, in Chelostoma, Osmia, 
Apathus, and Bombus. In Eucera and Sphecodes, each • 
joint of the flagellum is slightly curved, and in the 
former the surface of those joints appears compounded 
of hexagons. In Chelostoma the antennae, besides being 
longer than in the female, are also very much slighter 
and slightly compressed, and have a structure capable 
of curling upon itself; in the female of this genus the 
organ is clavate; and in Osmia, besides their length, in 
one species the male has a fringe of hair attached to 
one side along the whole of the organ. In other cases, 
where the antennae are not remarkably longer in the 
