56 Prof. C. Clans on the 



der kais. Akad. der Wiss. in Wien/ for 17th December, 1885, 

 and in the number of this Journal for February 1886. I 

 venture to reply as follows to these charges : — 



1. The communication published in the 'Anzeiger' upon 

 the relations of the Gigantostraca to the Arachnoidea, on 

 the unnatural character of the division into Brancliiata and 

 Tracheata, and on the classification of the Arthropoda, is 

 essentially nothing more than a repetition of my opinion as 

 already published years ago. Even in the work entitled 

 * Untersuchungen liber die genealogische Grundlage des 

 Crustaceensystems ' (Vienna, 1876) I adhei'ed to the views 

 of those who, like Straus-Diirckheira, regard Livmlus and 

 branchiate Gigantostraca as allied to the air-breathing Arach- 

 noidea, and the latter as having proceeded from the former, 

 although, having regard to the possibility of a still unde- 

 monstrated Nauplius-stage, I considered it probable that the 

 common origin with the true Crustacea was rather after than 

 before the Nauplius-period of the Stem-Crustacean. In the 

 case of Limulus and the Scorpions I also asserted the homo- 

 logy both of the six pairs of limbs of the cephalothorax and, 

 with reference to the developmental history, of the six pairs 

 of limbs of the prgeabdomen, of which the second pair repre- 

 sent the comb-like organ of the Scorpions, while the fol- 

 lowing four pairs immediately undergo retrogression (p. 110). 

 In the ' Grundztige der Zoologie ' of the year 1 880 I went 

 so much further as to divide the Branchiata, or Crustacea 

 sensu latiori^ into EuCRUSTACEA (with the Entomostraca and 

 Malacostraca) and Gigantostraca (with no certain traces 

 of the Nau])lius-stagej, and accordingly I affirmed expressly 

 of the Tracheata that in opposition to the more ancient Bran- 

 chiata they " icere not referable to a unitary oricjin^ since the 

 Arachnoidea, which are der ivahle from the Gigantostraca, stand 

 opposite to the Myriapoda and, Insecta, tohich are united by a 

 closer affinity''^ (p. 515). This implied not only that the 

 division of the Arthropoda into Branchiata and Tracheata is 

 an artificial one, inasmuch as the branchiate Crustacea and 

 the air-breathing Arachnoidea meet together in a common 

 origin, but also the denial of the unitary origin of the tracheae, 

 and the contrast of two series of Tracheata, the Arachnoidea 

 on the one hand, and the Myria])oda and Insecta on the other. 

 In his Limulus-i\Y{\c\Q E. Ray Lankester has entirely 

 ignored the contents of my work of the year 1876, and refer- 

 ring to the ' Grundziige,' cited by him, but with tlie contents of 

 which he was certainly unacquainted, he misrepresents my 

 views by the incorrect statement : " of the relationshi])s of the 

 Gigantostraca to Arachnida Claus says nothing." Altjiough 

 I will not reproach Prof. Ray Lankester with being so ill- 



