Till-; ANNALS 



AND 



MAGAZINE OF NATURAL HISTORY. 



[SIXTH SERIES.] 

 No. 88. APIUL 1895. 



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

 On the Position of the Acarina : The so-called Malpighinn 

 Tithes and the Respiratory Organs of the Arachnida. By 

 Julius Wagner *. 



The ]\Ialpigliian tubes and the respiratory organs of the 

 Arachnids liave 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 

 ]\Ialpighian tubes, and 1 have come to the conclusion that 

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

 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 

 trachece to a close investigation, and am now in a jjositioii to 

 assert that in no stage of the embryonic develoj)mentof Ixodes 

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

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

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

 known view as to the relationship of the Arachnids to Limu- 

 lus, we must unconditioiuilly adnnt that the common ancestor 

 of the Arachnids had no trachea^, the stigmata of which were 

 situated upon the cephalothorax ; anil we may therefore be- 

 lieve that in this respect the relation of the larva3 of the 



* Translated by E. E. Austen from the ' Jenaische Zeit'?cbi-ift fiir 

 NaturwisseiiscbaftV M. x.\ix. Heft 1 (Jena, 1894), pp. 12.3-15(). 



Ann. il; .1%. A'. Jlist. Ser. (i. Vol. xv. 20 



