THE ANNALS 



MAGAZINE OF NATUEAL HISTORY. 



[SIXTH SERIES.] 

 No. 88. APRIL 1895. 



man 



XXXV. — Contributions to the Phylogeny of the Arachnida.- 

 On the Position of the A carina : The so-called Malpigh 

 Tubes and the Respiratory Organs of the Arachnida. By 

 Julius Wagner *. 



The Malpighian tubes and the respiratory organs of the 

 Arachnids have attracted the attention of all students who 

 have devoted themselves to the study of the relationship of 

 the Arachnids to the remaining groups of Arthropods. For 

 this reason, in investigating the embryology of Ixodes I 

 directed my attention especially to the development of the 

 Malpighian tubes, and 1 have come to the conclusion that 

 in the Acarina, as I have shown in my Russian paper (No. 66, 

 p. 89), they are decidedly of endodermal origin, and that their 

 union with the rectum is only a secondary process. 



In a similar manner I submitted the development of the 

 tracheee to a close investigation, and am now in a position to 

 assert that in no stage of the embryonic development of Ixodes 

 is a structure to be found which can be regarded as the rudi- 

 ment of these organs of respiration, and that in reality tiie 

 larvae of Acarina have no trachese. If we adhere to the well- 

 known view as to the relationship of the Arachnids to LimU' 

 lus, we must unconditionally admit that the common ancestor 

 of the Arachnids had no tracheae, the stigmata of which were 

 situated upon the cephalothorax ; and we may therefore be- 

 lieve that in this respect the relation of the larvee of the 



* Translated by E. E. Austen from the ' Jenaische Zeitschrift fiir 

 Naturwisseuschaft,' Bd. xxix. Heft 1 (Jena, 1894), pp. 123-156, 

 Ann. i^ Mag. N. Hist. Ser. 6. Vol. xv. 20 



