Phylogeny of the Arachnida. 297 



the idea of the close relationship of the Scorpions to the 

 Crustacea." 



The signification of tlie coxal glands of the Arachnids as 

 excretory organs can scarcely be doubted after the experi- 

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

 34) ; uhilc in the case of the Insects thercJ/e of the excretory 

 organs devolves upon the Malpighian tubes and tiie |)eri- 

 cardiuni cells, and in the Myriopods upon the Malpighian 

 tubes iind certain cells of the fat-body, in the Arachnids, 

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

 great ])art. 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. Tho 

 signitication of the coxal glands of the Arachnids is evident 

 from the peculiarities observed in Phalantjium and the 

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

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

 described as Malpighian tubes (Plateau, No. b-^, p. 744), 

 were, as is well known, correctly compreliended for the tirst 

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

 manner it has been proved that the Phalangidte have no 

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

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

 Arachnida the coxal gland reaches its greatest and fullest 

 development in the Plialangidte : it attains a very great 

 volume, and its various jnirts 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- 

 lavcjium 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. The remarks of Winkler (No. 68) 

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

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

 of more attention. Tliis author describes in the Oribatidi\3 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 (" supcr- 



* For the literature on tlie subject of the coxal glands of Phalangium 

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



