206 T. THORELL, 
by several arachnologists. ‘They moreover on the whole form tolerably na- 
tural groups, although KoCH has not succeeded in giving any reliable dia- 
gnosis of them. I have determined on adopting the second, far more dif- 
ficult alternative, because I believe the division of the genus Attus WALCK. 
into several smaller genera to be a matter of great practical importance, 
especially on account of the great number of exotic species that have been 
described, and which furnish an amount of materials which it will be scar- 
cely possible to manage, unless one can distribute them among smaller 
generic groups. I am however by no means satisfied with the result of the 
experiment I have made, and the following arrangement, of the many de- 
fects of which I am perfectly conscious, must therefore be looked upon as 
merely provisional. It may however possibly, even if but negatively, con- 
tribute in some measure to the solution of the problem. None but a person 
having at his disposal far more comprehensive materials for research than 
I can command, can hope to arrive at any fully satisfactory result. 
All C. Kocn’s European genera have been here employed, with the 
exception of Zcelus ), which is founded on a feature (the back of the man- 
dibles raised to a sbarp ridge) belonging only to one sex, the males. Two 
of his sub-genera, Ballus and Dia (Ælurops NOB.) have been promoted to 
the rank of genera, the others I have been obliged to pass by. I have 
also endeavoured to give a place in my scheme to the genera Menemerus 
and Yllenus formed by SIMON. 
§ Pars cephaliea parte thoracica abrupte altior. Quadrangulus oculorum (ex 
oculis seriei 3%® et lateralibus seriei 1"? formatus) vix vel non longior quam 
latior. Corpus longum et angustum. Pedes tenues. . . . . . 1. Salticus. 
$8 Pars cephalica parte thoracica non altior. 
+ Quadrangulus oeulorum longior quam latior: oculi seriei 3"* fere in medio 
cephalothorace siti. Corpus longum et angustum; pedes tenues. 2. Leptorchestes. 
+t Quadrangulus oeulorum saltem postice latior quam longior. 
+ Metatarsi et tibi: omnes aeuleis carentes. Cephalothorax duplo fere lon- 
gior quam latior, humilis, dorso sub-recto. (Oculi seriei 1"? contingentes: 
medii eorum a margine clypei vix emarginati spatio brevissimo remoti ?). 
3. Epiblemum. 
1) The name Icelus was already in 1844 by Kroyer given to a genus of fishes. 
2) In order to judge rightly of the eyes' distanee from the edge of the elypeus 
and of the form of the latter, it is necessary to remove at least a part of the thick 
covering of hair which ordinarily conceals the edge: moreover the membrane, which 
unites the base of the mandibles, and which is sometimes covered with hair, and 
frequently visible under the edge of the clypeus, must not be reckoned as part of 
the clypeus. 
