INVESTIGATION OF INSECTS, 553 
read, and figures consulted, before its name can be in- 
disputably determined. In addition to the difficulty 
arising from the insufficient characters frequently given 
by Fabricius and the older authors, obstacles arising 
from their errors not seldom intervene. Thus they have 
sometimes selected for a specific character,—as in the case 
of Megachile centuncularis, Nomada ruficornis, and vari- 
ous other insects,—what really only indicates a family. 
At other times sexual characters common to many,—as 
in Eucera longicornis, Locusta perspicillata F., &c.,—have 
been had recourse to. In these cases, in order satisfac- 
torily to ascertain your species, you must further con- 
sult the synonyms and habitat given by the original de- 
scriber, especially the figures he has referred to. When 
all these fail, as they sometimes will, the dernier resort 
is a reference to the cabinet containing the original spe- 
cimen from which the description was drawn. British 
Entomologists possess an invaluable privilege, which 
their continental brethren may well envy them, in having 
the most liberal access, indulged to them by the learned 
President of the Linnean Society, to Linné’s collection 
of insects, from which a large proportion of the species 
he described may be ascertained. Several of the cabi- 
nets, especiaily the Banksian,—now the property of the 
Linnean Society,—from which Fabricius described his 
insects, may also still be consulted; and thus many mis- 
takes rectified, which would otherwise greatly mislead*. 
Though sometimes the limits that separate good spe- 
@ It may not be amiss to mention a few :—Spheridium dytiscoides 
is a Hydrophilus related to H. fuscipes. S. glabratum is heteromerous, 
probably one of the Helopii Latr. Carabus retusus and Madere both 
belong to Calosoma. Cistela angustata is a true Choleva. See Linn. 
Trans. xi. 138.—S. 
