Phylogeny of the Arachnicla. 297 



the idea of the close relationship of the Scorpions to the 

 Crustacea." 



The signification of the coxal glands of the Arachnids as 

 excretory organs can scarcely be doubted after the experi- 

 ments of Kowalewsky upon the Scorpion (Nos. 32, 33, and 

 34) ; while in the case of the Insects the role of the excretory 

 organs devolves upon the Malpighian tubes and the peri- 

 cardium cells, and in the Myriopods upon the Malpighian 

 tubes and certain cells of tlie fat-body, in the Arachnids, 

 besides the latter, the liver and the coxal glands also play a 

 great part. Even if these glands are homologous in the 

 Myriopods and the Arachnids — a question which does not 

 enter into the scheme of my observations — the part played by 

 them in the two classes is nevertheless not the same. The 

 signification of the coxal glands of the Arachnids is evident 

 from the peculiarities observed in Phalangium and the 

 Acarina. The coxal glands of Phalangium (or, more cor- 

 rectly, the tubular portion of them), which were previously 

 described as Malpighian tubes (Plateau, No. 53, p. 744), 

 were, as is well known, correctly comprehended for the first 

 time by Loraan (No. 42 a, pp. 93 et seq.^), and in this 

 manner it has been proved that the PhaU^ngidse have no 

 Malpighian tubes, " Apparently," says Faussek (No. 14, 

 p. 82), "from a morphological standpoint, among all the 

 Arachnida the coxal gland reaches its greatest and fullest 

 development in the Phalangidge : it attains a very great 

 volume, and its various parts are distinctly defined and 

 strongly developed. At the same time its physiological 

 significance is probably very considerable." The absence of 

 Malpighian tubes and the presence of coxal glands in Pha- 

 langium must evidently be regarded as phenomena which are 

 mutually dependent upon each other. Quite the opposite 

 conditions are found in the majority of the Acarina ; in this 

 group the Malpighian tubes are relatively strongly developed, 

 but up to the present time the existence of coxal glands has 

 not definitely been proved. Tlie remarks of Winkler (No. 68) 

 and Henkiug (No. 20) are not sufficiently precise : the state- 

 ment made by Michael (No. 46, and No. 45, p. 178) is worthy 

 of more attention. This author describes in the Oribatidse a 

 gland situated at the base of the second pair of legs, and in 

 a general way recalling the coxal glands of the rest of the 

 Arachnida ; yet it is precisely these forms that, according to 

 Michael's description, possess no Malpighian tubes. Michael 

 did not succeed in discovering an orifice to the coxal (" super- 



* For the literature on the subject of the coxal glands of Phahmfjium 

 down to the year 1890, see Faussek's memoir (No. 14, pp. 69-82). 



