igos.] EXCRETORY ORGANS OF METAZOA. 593 



reaches to and opens upon the skin, then later loses this opening; 

 Brauer found that a series of them arise, in segments third to sixth, 

 inclusive, but that all but those of the fifth segment soon disappear. 



(3) CypJwphthalmidea. 



Malpigliian Vessels. — There is one pair of these in Gibocelluin, 

 opening at the junction of the mid-gut and hind-gut; they are of 

 great size and each is remarkable in having a net-like branching at 

 its middle only (Stecker, 1876). 



Coxal Glands. — Sturany (1891) holds what Stecker called 

 " Speicheldriisen " to be probably coxal glands ; there is one pair 

 of them on the sides of the stomach. 



(4) Phalangida. 

 There are here no Malpighian vessels, and their absence is due, 

 according to Loman (1888), to the functional persistence of the 

 coxal glands. The latter are organs with an inner closed end sac 

 (Faussek, 1892), that open in the Opiliones laniatores behind the 

 third, and in the Opiliones palpatores and Chelonethi behind the 

 fifth extremity. They develop as mesoblastic outgrowths of the 

 particular extremities in which they are placed (Sturany, 1891, 

 Faussek, 1892). 



(5) Pseudoscorpionidea (CJiernetidcc). 



Here also there are no Malpighian vessels. The coxal glands 

 are stated to have no exterior openings, to lie at the base of the fifth 

 extremity, and to be of mesoblastic (nephridial) origin (Sturany, 

 1891). The spinning glands that have two pairs of opening on the 

 chelicera are considered by Bertkau (1888) to be homologous with 

 them. 



(6) SolifugcB (Galeodidcu). 



Malpighian Vessels. — These are one pair of branched tubes. 



Coxal Glands. — There is one pair placed between the third and 

 fourth coxae; Bernard (1893) considered the end sacs to be pro- 

 longations of the ducts, but his account is not convincing. Loman 

 (1888) has suggested that the poison glands are homologous with 

 them. 



