with Descriptions of New Species. 191 
is hot correct; for the first three joints of the anterior 
tarsi in the males of Cycurus viduus, tuberculatus, cris- 
tatus, and margindtus are dilated, and together with the 
smaller fourth joint are furnished with brushes beneath. 
Indeed, in form and structure these parts aré scarcely 
to be distinguished from the anterior tarsi in the males 
of ScaPHiNOTUs. A similar structure is visible in the 
tarsi of Cycnrus rostrátus, the only European species 
of which I have seen a male; but the dilated joints are 
proportionally smaller than in our American species. 
he only remaining character by which the genus Cv- 
CHRUS is distinguished from Scaruinotus is the form of 
the margin and of the posterior angles of the thorax ; in 
Cycurvs, it is stated that the lateral margins of the tho- 
rax are not raised, and the €: angles are rounded 
and not prodüced behind ; whilejin Scaemiworus the 
lateral margin is said to be ran up, and the posterior 
angles are acute and prolonged backwards. Now in . 
Cycurvs viduus, and still more remarkably in a new 
species, which remains to be described, the lateral mar- 
gins of the thorax are wide, and evidently elevated, par- 
ticularly behind ; and the posterior angles extend more 
or less beyond the basal edge of the thorax, though they 
are not much produced backwards. On the other hand, 
in our new species of ScaenrNorvus, the lateral margins 
of the thorax are ‘much less raised than in the typical 
species elevátus, and the posterior angles are wider, not 
so acute, and not so much prolonged behind. Will 
these slight and variable differences in the form of the 
thoracic margins and posterior angles be considered 
sufficient tó establish a genus, in the bsicne of all other 
distinguishing characters ? 
