2 TERRESTRIAL CARBONIFEROUS ARACHNIDA. 



powerful chelate palpi. But in addition to these efficient prehensile organs the 

 Scorpiones have a poisonous sting ; the Uropygous Pedipalpi have protective acid- 

 glands at the tip of the opisthosoma, while the Amblypygi are extraordinarily 

 quick in their movements and have a highly specialised tactile organ in the legs of 

 the first pair. The Araneas have probably survived in virtue of their snare- and 

 cocoon-making spinning glands, coupled with poison-glands in the mandibles ; and 

 there is some evidence that existing Opiliones are protected by their scent-glands. 

 Since there is no reason to suppose that the members of the extinct orders above 

 enumerated had specialised glands either for offensive or defensive purposes, and 

 since their palpi were short and non-prehensile, and their organisation suggests that 

 they were comparatively slow-moving, cryptozoic forms, it might be supposed that 

 these atti'ibutes supply the needed explanation, were it not that the Ricinulei re- 

 semble them in most of these particulars. One thing, however, must not be for- 

 gotten. An important factor in the evolution of terrestrial Arachnida has been, in 

 my opinion, a change from the method of pairing, as practised by Scorpions, to new 

 and special methods, resulting in the modification of a part of one of the prothoracic 

 limbs into an intromittent organ, often of great complexity. This may be seen in 

 the Araneas, where the palpi are modified, in the Solifugaa, where the mandibles 

 are modified, in some of the Acari, and lastly in the Ricinulei, where the legs of the 

 third pair are modified. Even the Opiliones possess very special secondary repro- 

 ductive organs. There is no evidence, nor any reason to suppose, that the 

 Haptopoda, Phalangiotarbi, or Anthracomarti had departed from the normal in 

 their breeding habits; and it is quite conceivable that the Ricinulei have outlasted 

 their Carboniferous contemporaries belonging to those three orders on account of 

 their very specialised methods of copulation. 



Up to the present time the only orders of Arachnida known to be represented 

 in British Carboniferous strata, belong to the Scorpiones, the Phalangiotarbi, and 

 the Anthracomarti. Of Scorpiones several species have been described, mostly by 

 Dr. Peach from Scotland ; one species of Phalangiotarbi was named many years 

 ago by Dr. Woodward ; while of Anthracomarti some five species have been made 

 known by Dr. Woodward and myself. As an historical fact it is interesting to 

 record that in 1826 Dean Buckland described two Arachnida as Coleopterous 

 insects. One of these was detected to be an Arachnid by Dr. Woodward, and the 

 other I have now been able to identify as also belonging to that class. 



The material at my disposal has shown that the British Carboniferous fauna is 

 at least as inch in species and genera of Arachnida as that of Continental Europe 

 and North America, the species of which have been described for the most part 

 respectively by Kusta and Fritsch and by Scudder. Fritsch can hardly be acquitted 

 of the charge of needlessly creating species and genera. Scudder's work on the 

 contrary is open to no such accusation. It appears to me that in the present state 

 of our knowledge of this group, species in themselves are of very little importance. 



