310 Mr. R. 1. Pocock on Liphistius and its 



Hexathele have moved forwards internally and not exter- 

 nally. This question, however, presents many difficulties in 

 the way of its solution, and requires far more attention than 

 I have so far been able to bestow upon it. Enough, how- 

 ever, has, I think, been said to show that, so far as the 

 spinning-organs are concerned, Liphistius seems to approach 

 the Dipneumones more nearly than the Territelarise. 



If this view as to the correspondence between the criheUum 

 and the anterior auxiliary mammillas of Liphistius is correct, 

 it has I think an important bearing on the classification of 

 spiders. 



In 1886 Dr. Thorell * gave a concise sketch of the views 

 of his predecessors and contemporaries on the subject of the 

 classification of the Aranese. The object of this paper was 

 the refutation of the system proposed by that eminent ento- 

 mologist Dr. Bertkau ; and at the end of his criticisms 

 Dr. Thorell put forward a classification of his own, introducing 

 sundry changes into that which he had previously used, in 

 accordance with the greater value that was attached by 

 Bertkau to certain structural features that Thorell had 

 previously looked upon as of secondary importance. 



In this new system the old divisions of spiders into Tetra- 

 pneumones and Dipneumones is adopted. For subdivisions 

 of the Dipneumones the old tribal names Tubitelariae, Orbi- 

 telarise, Citigradse, &c. are retained, the two former being- 

 subdivided into Cribellataj and Ecribellatge, according as the 

 crihellum (and calamistrum) are present or not. The Tetra- 

 pneumones contain the single tribe Territelarise, embracing 

 the families Liphistiidee, Theraphosidag, and Atypidse. 



In its main characters this classification has been adopted 

 by Dr. Marxf, in his 'Catalogue of North-American Spiders.' 

 One modification, however, is the introduction into the 

 Tetrapneumones of the remarkable genus Hypochilus^ for 

 which a new tribe^ Umbellitelarige, is established. Moreover, 

 Dr. Marx appears not to attach so much importance as 

 Dr. Thorell to the presence of the criheUum and calamistrum. 

 Furthermore he adopts Dahl's tribe Plagitelarige for the Phol- 

 cida;, and creates a new tribe, Filite] arise, for the Dysderidge, 

 Filistatidse, and Scytodidae. 



In 1891 Dr. Thorell % favoured us with fresh views on 

 the subject. He forms a new tribe of Tetrapneumones, 

 named Verticulatse, for Liphistius, and retains Hypochilus 



* Ann. & Mag. Nat. Hist. (5) xvii. pp. 301-326. 



t Proc. U. S. Nat. Mus. xii. p. 498 (1889). 



X Koiigl. Sv. Vet.-Akad. Handl. xxiv. no. 2, pp. 8, 9. 



