THE ANNALS 



AND 



MAGAZINE OF NATURAL HISTORY. 



[FIFTH SERIES.] 

 No. 100. APRIL 1886. 



XXVIII. — On Dr. Bertlcau^s Classification of the Order 

 Aranece, or Spiders. By Prof. T. Thorell, 



It is a well-known fact that a natural classification of the 

 Spiders — which form the best studied, the most numerous, and 

 perhaps the most interesting Order of the Class Arachnida — 

 is a problem, the solution of wliich otFers very great difficulties, 

 and that a generally adopted system of classification of these 

 animals is therefore still a desideratum. Most of the older 

 arachnologists, such as Lister, Clerck, De Geer, and, at first, 

 even Latreille*, based the distribution of the Spiders into higher 

 groups, not on differences in their organization^ but on certain 

 peculiarities in their habits, especially on their mode of loco- 

 motion and the form of their webs. Against this principle 

 of classification the objection may be reasonably made that it 

 is rather unscientific, not being founded on characteristics 

 taken from the animals themselves ; it has nevertheless been 

 maintained by some more recent authors as the basis of their 

 classifications. It may at first sight appear difficult to under- 

 stand the reason of thus adhering to a principle which in 

 other departments of zoology is generally and justly abandoned, 

 if ever made use of; but I think it may easily be explained 

 by the fact that the differences in tlie form of the web and the 

 mode of locomotion which the Spiders exhibit correspond, upon 

 the whole, with a peculiar " habitus " and with modifications 



* In Cuvier, ' Le Regne Animal, distribue d'apres son Organisation,' 

 iii. (1817). 



Ann. & Mag, N. Hist. Ser. 5. Vol. xvii. 21 



