COLEOPTEROUS FAMILY PAUSSID_E. 165 
time taken out the labium of only one species of this genus, of which 
the anterior margin was quite simple, I was induced to believe 
that in describing the labium as 3-dentate, Latreille had mistaken 
the two spines at the anterior margin of the mentum or gula trian- 
gularis for part of the labium. Having, however, recently dis- 
sected P. microcephalus, which appears to have been the species 
which he dissected (as he gives it as his first example of the genus, 
having received it from Mr. MacLeay), I find that its labium 
accords with Latreille’s description. As to the part which I have 
regarded as the mentum (a part which Latreille states is wanting), 
it may be contended that the two porrected spines represent the 
produced undersides of the head, or undercheeks peculiarly 
developed, as in Catogenus, Passandra and Megagnathus ; but 
as the true mentum is occasionally soldered to the head (as in 
Siagona), and as the maxille arise at the outersides of the pro- 
duced spines (thus agreeing with the typical structure of the 
Coleoptera, where the base of the maxille arises at the outerside 
of the mentum), I have the less hesitation, especially after a com- 
parison of this part in this genus and in the preceding, in regarding 
the gula triangularis as the representative of the mentum. 
As regards the external sexual marks of distinction in this 
genus, I am only able to state, that, according to Afzelius, the 
female of P. sphcerocerus differs chiefly from the male in having 
the labial palpi rather narrower, the produced lobes or spines of 
the mentum glaucous, the maxillary palpi shorter, with the second 
joint narrower, the abdomen longer, and the posterior femora 
slenderer. In some individuals, we find the extremity of the 
abdomen furnished with two acute curved diverging spines, which, 
I believe, will be found to be a sexual peculiarity. 
The species of this genus are much more numerous than those of 
any of the other genera. Some of them, possessing a subcontinuous 
prothorax, and a broad clava to the antenna, are closely allied to 
the Platyrhopali; whilst others, with a bipartite prothorax, seem 
to approach Pentaplatarthrus, although the structure of the palpi, 
maxillze, &¢., of the last-named genus (sce pl. 58, fig. 2, details) 
materially differs from that of the true Paussi. 
Of the habits of this genus we possess but little information ; 
sufficient, however, appears to be known to lead us to infer that 
the species are nocturnal in their habits, being often attracted by 
the light in houses after dark, and that, like Claviger, Lomechusa, 
