ON EUROPEAN SPIDERS. 15 
is generally known, not applied, and I have accordingly, in conformity with 
the practice of most modern arachnologists, adopted SUNDEVALLS denomina- 
tions, derived from the most prominent genus within the family, employing 
however the termination -oide, as being more etymologically correct than -1- 
des or -ide. — I have no doubt in many points been guilty of real mistakes, 
but I venture nevertheless to hope for a mild judgement from persons acquaint- 
ed with the subject, who are aware of the difficulties to be encountered in a 
work like the present. I ought especially to remark, that I have been un- 
able to determine with certainty the exact date of the publication of some 
of the arachnological works here cited; this has been especially the case 
with a couple of works published in numbers without date, as also with some 
papers published in periodicals. As regards these latter, I have in dubious 
cases assumed the year for which the periodical is published, as the date of the 
articles it contains, though in many instances this may not be right, because 
the latter numbers of a journal commonly appear the year following. When 
the year of a work’s printing is expressed, I have of course accepted that 
as the date of publication, whenever I did not know with certainty that 
such date was incorrectly given 2). 
In restoring the first or original specific names I have endeavoured 
to observe all the cautiousness so necessary in such a process. The species 
of the older writers are, as is well known, often difficult, sometimes im- 
possible to determine with certainty: with respect to them I have, in appli- 
cable cases, laid it down as a rule to preserve the determinations accepted 
by modern arachnologists who have lived in the country where the species 
described by the author in question have been collected. It is evident that a 
French naturalist has the best opportunities for studying the French spiders 
described by Fourcroy, DE VILLERS, LATREILLE etc., a German the Ger- 
man species of SCOPOLI, FABRICIUS and PANZER, and so forth, as also we 
Swedes ought to be best acquainted with the Swedish forms described by 
CLERCK, LINNÉ and DE GEER. Tradition has here a significancy that 
must not be undervalued. It is only in cases in which I have supposed 
myself able to show that an evident mistake has been made, that I have 
deviated from this rule ?). 
1) This is for instance the case with WALCKENAER'S Hist. Nat. d. Ins. Apt., 
Tome II, which bears on its titlepage the date 1837, but did not come out till 1841. 
2) Regarding the rules, which, in determining the species of the older authors, 
ought in doubtful cases to be applied, I beg to cite the following from Ree. Crit. 
Aran.: "...maximi nobis esse momenti crediderim penitus cognovisse, quæ forme in 
iis regionibus gignantur, ubi vixerit et animalia collegerit scriptor, eujus species sint 
