118 . Mr. H.W. Bates on the Longicorn Coleoptera . . ~ 
joint—a feature characteristic of the genus Hthomerus. 4. La- 
cordairet differs from the other species in having straight fore 
tibize, and in having rather less elongated antennz, whose arti- 
culations are much shorter in the ? than in thed. 
The species are nocturnal in their habits. They are of rare 
occurrence, and are found in the daytime crouched on leaves,— 
Ai. Lacordairei, however, being seen only closely adhermg to 
decayed boughs. In those species which have strongly bowed 
fore tibize, the anterior femora are greatly enlarged and furnished 
on the inner side with a sharp ridge, which fits a corresponding 
groove along the tibie. In the crouching position, the fore legs 
are closely folded, the almost invisible antennz laid backwards, 
and the whole insect assumes a rigid aspect, well calculated to 
deceive its enemies. 4. Lacordairei, on the other hand, possesses 
passive means of defence of quite a different character: its co- 
lours and markings give it a deceptive resemblance to a dead 
pupa covered with a fungous growth, such as is often seen ad- 
hering to trees in damp climates. The deception is perfect, the 
insect having on each side of its body a large spot coloured and 
reticulated like a wing seen through the integument of a pupa. 
Thus we see here another instance of the widely different means 
Nature employs, within the same genus, to maintain the exist- 
ence of her specific forms. very species exists by virtue of 
some endowment which enables it to triumph over the infinite 
diversity of adverse circumstances that surround it at all stages 
of its life. This concerns us here, inasmuch as the general 
principle has an important bearing upon the systematic arrange- 
ment of species, a knowledge of the fact that structures are 
adapted to the ends just mentioned being necessary to avoid 
errors in estimating their affinities. Longicornes are greatly 
subject to these adaptations, those parts of structure being mo- 
dified, from species to species, on which we depend for the esta- 
blishment of genera, thus rendering, in this family, real generic 
definitions almost impossible. 
1. Aithomerus antennator, Fabricius. 
Lamia antennator, Fab. Syst. Eleuth. ii. p. 288. 36. 
4B. clongatus, tenuiter tomentosus, niger vel brunneus, variegatus : 
_ elytris ineequalibus, lineis tenuibus argenteo-albis inscriptis, basi 
elevatis, apud medium subnudis nitidulis. Mas segmento ultimo 
ventrali simplici: foemina eodem fovea magna impresso. Long. 
_ 34-42 lin. SQ. 
Head dark brown. Antenne pitchy brown, the apices of the 
joints paler. Thorax with two dorsal tubercles in a transverse 
line with the lateral ones, all ur of equal size; the surface 
punctured ; dark brown or blackish, varied with lighter brown. 
