Phylogeni/ of the Anichnida. 31 I 



aiul PIialangidji3 (unquestionable forms) first occur in tlic 

 (Jc-nozoic (k'posits (Zittel, loc. cit.^ adapted from jSciidder). 

 As I ])reviously stated, it appears to me very probable that 

 the Araehnida have divided into two branches ; of these the 

 one with the Scorpions at its extremity served to give rise to 

 the Pcdipal|)i and the Araneae, while from the other, in which 

 forms standing midway between the Pseudoscorpions and the 

 Solifugre belong to the more primitive types, arose the rest of 

 the Araehnida*. In the case of the former group there 

 exists in the embryonic or even in the postembryonic period 

 a distinctly segniented jjostabdominal division, while the 

 function of respiratory organs is discharged by lungs (meta- 

 morphosed branchije) and partly by modifications of these 

 organs (Dipneumones) ; in the latter no postabdominal 

 division can be distinguished (with regard to Chelifer^ cf. 

 No. CG, pp. 157-158), the respiratory organs are represented 

 exclusively by tracliea, which moreover are not infrequently 

 dendriform, while in many cases the stigmata are situated in 

 the cephalothorax. 



As to the mutual relations of the various orders in each of 

 the groups mentioned, but especially in the second, we can in 

 the present state of our knowledge of their development only 

 form a partial judgment. In the first group the Aranefe, in 

 the second the Acarina, are most divergent ; in this way the 

 relation of the Aranca3 to the Scorpions in the first group is 

 the same as that of the Acarina to the Pseudoscorpions and 

 the Solifugffi in the second. If we disregard the little-studied 

 Cyphophthalmidje (and Gihbocellum), we may regard the 

 Phalangidai as a branch of the primitive stem of the second 

 grouj) of Arachnids, which separated at a very early period ; 

 their ancestors were probably very closely allied to certain 

 Anthracomarti (families Architarbidaj and Eophrynidte) t of 

 the Coal-measures. 



♦ The position of the Tardij^rades i.«, as it st'i'ius to mo, still altogether 

 indefinite (cf. the parallels between the Tardii^aades and Insect laivie, as 

 stated by von Kennel, No. i'7). 



t The order of Arachnids that occurs in the Coal-measures, the 

 Anthracomarti of Scudder, is apparently an altofjrether artiiicial frroup. 

 This is already indicated by the too con>iderable difference in the iiumber 

 of the abdomnial sefrnients in the various representatives of the j^roiip (in 

 certain cases four, in others as many as nine), while a comparison of the 

 various views on ihe subject of the Anthracomarti also lends to the same 

 conclusion. Karsch (No. :i."{, p. oof^) assumes, on the basis of his own 

 observations, that through Viot»lijcn»a of the Carboniferous period and 

 the existing Li/ihisfius, Autfiracomnitus forms a direct transition to the 

 typical unsegniented Arane.T, while he regards the interesting fos.sil 

 Kreiscfiena as a form very near akin to the existing Trogulidie. Hy 

 llaase (No. 17), however, the majority of bcudder"s Authracomurli are 



