592 MONTGOMERY— MORPHOLOGY OF THE [Apnl 24, 



Coxal Glands. — Evidently these are not functional but are de- 

 generate in the adult; Bruntz (1903) has proved they are excretory. 

 In the young of Atypus there is a pair of these opening on the third 

 coxas (Sturany, 1891), but the duct is lacking in the adult (Sturany, 

 Bertkau, 1885). In the young of Mygale Loman (1888) states it is 

 degenerate, while Pelseneer (1885) finds no ducts but on each side 

 of the body a four-lobed gland corresponding to the four extremities 

 of the thorax. Sturany and Hansen and Sorensen ( 1904) state 

 that in the Tetrapneumones it opens behind the fifth extremity 

 (third leg) and in the Dipneumones behind the third (first leg). 

 Kishinouye (1890) maintained that these organs arise from the 

 ectoblast, though he showed that the anlage opens by a funnel into 

 the coelom. 



Genital Ducts. — Purcell (1895) has shown that these arise as 

 evaginations of the coelomic sacs ; " the similarity of their develop- 

 ment with that of the coxal glands in Arachnids generally indicates 

 their nephridial origin." 



Hind-gut. — This is said to serve as an excretory organ until the 

 Malpighian vessels are developed ( Bertkau ).** 



(2) Scorpionidea. 

 Malpighian Vessels. — These are branched, four in number 

 (Dufour, 1854) ; though generally supposed to have the same func- 

 tion as those of other arachnids they are stated by Bruntz (1889) 

 to be not urinary. They arise from the entoblastic mid-gut (Brauer, 



1895 V 



Honiologncs of Nephridia. — The genital ducts develop like and 

 are homodynamous with the coxal glands (Brauer, 1895). The 

 latter are in one pair and open behind the fifth extremity (third 

 leg) ; Bruntz has shown that they have an excretory function. These 

 have each a narrow duct and an enlarged inner end sac. Bernard 

 (1893) held these glands to be ectoblastic, independent of the coelom, 

 homologues of acicular glands. But the researches of Laurie 

 (1890), Sturany (1891) and Brauer (1895) have demonstrated that 

 they arise each as an outpushing of the somatic mesoblast that 



* The spinning glands are ectoblastic, and may be equivalent to crural 

 glands, but are neither excretory nor nephridial. 



