and Classification cf the Opiliones. 507 



enaLling us to classify tliese four fauiilies into two groups. 

 Tliese I propose to call Apagostenii and Eupa;^osterni *. 



In none of the systematic works quoted above have I found 

 the sterna of the Nemastoniida3 and Trogulidaj described. 



In speaking of the sternum of the Opiliones in general, 

 Simon confined his remarks, so far as the Plagiostethi (Palpa- 

 tores) are concerned, to the Phalangiida3 {loc. cit. p. 121). Had 

 he examined the sternum in TroguluSj Neunstoma, and Di- 

 craiiolasma^ he would hardly have described this plate as 

 " tr^s-court, transverse" (p. 157) in the Plagiostethi. In 

 short, his account of the Plagiostethi contains no statement 

 of the structural differences pointed out above. 



Thorell, on the other hand, appears to have searched for 

 the sternum at least in Trogulus, but with what measure of 

 success may be gathered from his statement that in this genus 

 two small oblique laminae, meeting at an angle in front and 

 united to the base of the coxjb of the first pair of legs, seem to 

 take the place of the sternum and labium (p. 468, 1876). 

 'Jhese " oblique lamina? " are the thickened and elevated edges 

 of the coxfB in question. 



In the present year (Zool, Anz. xxv. p. 445) Borner 

 writes : — " Auch bei Trofjulus tricarinatus fand ich keine 

 Unterlippe, aber ebenfalls kein eigentliches Sternum; die 

 Ohitinhaut zvvischen den Hiiften der 4 letzten Beinpaare ist 

 nur schwach und gleichmassig chitini*iert und kauni als 

 Sternum aufzufassen ; hier schliessen die Ooxalfortsatze der 

 3 Extremitat den Mund hinten ab. Bei Nemastoma findet 

 man ein kleiues Sternum zvvischen den Hiiften der 3 Extre- 

 mitat, hinter den Coxalfortsiitzen; es ist ohne labiale Function, 

 die von den Kauladen der 3 Extremitat ausgeiibt wird; an- 

 dere sterna fehlen hier. . . . Da der Genitaldeckel . . . 

 zwischen den Hiiften . . . des letzten Beinpaare [Trogulus^ 

 Nemastoma^ Phalangidaa etc.) liegt . . . fehlen bei den 

 Opiliones melst das Tetra-, Penta- . . . und Metasternum " 

 [= sternal plates of the somites of the prosomaj. And in the 

 table (p. 439) showing the persistence and suppression of the 

 sternal plates in various genera of Arachnida the sterna of 

 the third and fourth somites [i. e., represented by the first 

 and second pairs of legs] in Trogulus are bracketed as 

 " schwach chitinisiert," those of the fifth and sixth as re- 

 placed by the genital plate ; in Nemastoma that of the third 

 [?'. e., the labium'] is indicated as present, those of the fourth, 

 fifth, and sixth bracketed as replaced by the genital plate. 



* aTrayr]^, loosely knit or unfixed; evnayris, -well fixed or firmly knitj 

 and artpvov, the breast. 



