436 ARACHNIDA—CHERNETIDEA CHAP. 
Classification.—The order Chernetidea consists of a single 
family, Cheliferidae. Nine genera are recognised by most 
authors, but their grouping has been the subject of a good deal 
of difference of opinion, largely dependent on the different 
systemic value allowed by various arachnologists to the absence 
or presence of eyes, and to their number when present. Simon 
takes the extreme view that the eyes are only of specific value, 
and he is thus led to suppress two ordinarily accepted genera, 
Chernes and Roneus, which are separated chiefly by eye-characters 
from Chelifer and Obisium respectively. He relies rather on 
such characters as the presence or absence of galea, epistome, and 
trochantin, and establishes three sub-familes as follows -— 
Gi.) CHELIFERINAE.—Galea. No epistome. Trochantin ou 
all legs. Eyes two or none. Sole genus, Chelifer (Chelifer 
+ Chernes). 
(i.) GARYPINAE.—Galea. No epistome. Trochantin on legs 
3 and 4 only. Eyes four or none. Genera Chiridiwm, Olpium, 
and Garypus. 
(i1i.) OBISIINAE.—No galea. An epistome. No trochantin. 
Genera Chthonius and Obisiwm (which includes Roncus). 
Whatever be the value of the eyes in the classification of this 
group—and Simon adduces strong arguments for his view— 
there can be no doubt of their convenience in practical identifica- 
tion. Moreover, as Pickard-Cambridge! points out, a grouping 
of the genera according to the eyes results, as regards British 
species, in pretty much the same linear arrangement as Simon’s 
classification, and it may therefore be convenient to mention that, 
of the six genera represented in this country, Chthonius and 
Obisiwm are four-eyed, Roneus and Chelifer two-eyed, while 
Chernes and Chiridium are eyeless. 
Sub-Fam. 1. Cheliferinae—These Chernetidea have the 
cephalothorax slightly narrowed in front, and generally marked 
dorsally with two transverse striae, while the abdominal plates 
are bisected by a dorsal longitudinal line. With the exception of 
Chelifer cancroides, which is always found in houses, all the 
species are to be sought under bark, though occasionally they are 
discovered under stones. 
The two genera of this sub-family are Chelifer and Chernes, 
the species of Chelifer being two-eyed, and those of Chernes blind. 
1 Monograph of the British Species of Chernetidea, Dorchester, 1892. 
