TYPE ARACHNID A. 459 



single pair leading into tracheae ; many forms parasitic ; fre- 

 quently with complicated metamorphoses. 



Nonparasitic, or parasitic only iii larval stage ; terrestrial. Ori- 

 bates, Nothrus, Trombidium. 



Aquatic. Hydrachna, Atax. 



Living on organic matter. Tyroglyphus. 



Parasitic on animals. Demodex, Sarcoptes, Dermaleichus, Anal- 

 ges, Gamasus, Ixodes. 



Parasitic on plants. Tetranyclms, Phytoptus. 



LITERATURE. 



GENERAL. 



H. Grenacher. Untersuchungen ilber das Sehorgan der Arthropoden. Gottingen, 

 187 ( J. 



E. R. Lankester. Limulus an Arachnoid. Quarterly Jouru. Microscop. Sci- 

 ence, xxi, 1881. 



J. Macleod. RecJierches sur la structure et la signification de I'appareil respira- 

 toire des Arachnides. Archives de Biologic, v, 1884. 



R. Sturany. Die Coxaldrilsen der Arachnoiden. Arbeiten a. d. Zoolog. Inst. 

 Wien, ix, 1891. 



J. S. Kingsley. The Embryology of Limulus. Part II. Journ. of Mor- 

 phology, vni, 1893. 



SCORPIONIDA. 



L. Dufour. Histoire anatomique et physiologique des Scorpions. Memoirs 

 Acad. Sciences. Paris, xiv, 1856. 



E. R. Lankester. On the Coxal Glands of Scorpio, etc., and the Brick-red 

 Glands of Limulus. Proceedings of the Royal Society, xxxiv, 1884. 



G. H. Parker. The Eyes in Scorpions. Bulletin of the Museum of Compar- 

 ative Zoology, xni, 1879. 



W. Patten The Origin of Vertebrates from Arachnoids. Quarterly Journal 

 of Microscop. Scieuce, xxxi, 1890. 



M. Laurie. The Embryology of a Scorpion (Euscorpius italicus). Quarterly 

 Journ. Microscop. Science, xxxi, 1890. 



PSEUDOSCORPIONIDA. 



A. Croneberg. Beitrag zur Kenntniss des Baues der Pseudoscorpione. Bulletin 



Soc. Imp. Naturalistes Moscou, 11, 1888. 



SOLIFUG.E. 



L. Dufour. Anatomie, pJiysiologie, et histoire naturelle des Galeodes. Me- 

 moires Acad. Sciences, Paris, xvii, 1858. 



PHALANGIDA. 



B. Rossler. Beitrage zur Anatomie der Phalangiden. Zeitschrift fur 

 wissensch. Zool., xxxvi, 1882. 



