No. (i2.)i TllK KVOIJ TIOX or MiT II HOI'ODS 153 



poda are structin-allx- .jnitc far vcitioxcd t'l-oiii the arach- 

 nids exaiiiiiu'd by him, and since he lias iiuuh' a very 

 extensive study ol" the different arachnoi.l forms, his 

 opinion should liave eonsiih-raltle wei-iit. Since tlioir 

 line of development does not ap]»idacli \-ei-y ch)>ely to 

 those of the oViwv forms liere di.M-n^MMh the ^tudv of the 

 Panto])oda is not of as ,o,,.at phy h.uvnet i.- importanc.. as 

 tliat of those forms wlii.-1i o<-cnpy a i)nsition aimectent 

 between the otlior -roups, or wlm^c lines of (h-c.mt a])- 

 ])roacli tliose of tlie other -ronp^. tlie purpn^' of 



tlie present paper, it is therefoiH' -nihcient to sa\ that 

 the Panto])oda represent a lii,ahl>- a1)eriant uren]* whose 

 line of descent hranched off at an early date, soniewliere 

 near the Trih)bita-]\rerostomata group, and that they 

 have followed a widely <livergent path of specialization. 



The scor].ion> are (hv-cended from forms very like the 

 enrypterid ineni])ei s of the Trilohita-Merostomata group, 

 and such euiwpterids a- (llt/ptosmrp'nis occupy a ])osi- 

 tion annectent between the two gi-onps. On the other 

 hand, the s,M,r].ions, togetluT with the Pedii.alpi. are in 

 many respeets very like tlu' an.-estors of the higher 

 ai'achnids. so that they form an anc.-tral group, the 

 Scoi'pionida [*e<lipal}.i. intermediate between th(> Trilo- 

 i)ita-.Mero^toniata group and the higher arachnid^. In 

 the Seorpionida-IN'dii.alpi uroup should be inclu.h'd tlie 

 elo>ely allied p>emlo>corpions and ]n'obably the Kn^ur- 

 ■uia-Wkv forms and the Solifugie also. 



Of the higher grou]» of arachnids, the spiders (Ara- 

 nea^) are ai.parently <piite closely related to the ambly- 

 I'igid (tarantulid) branch of the Pedii-alpi. while the 



rehited to tlie pseudoM-orj .ion^ and Solifn-a-. although it 



}M)sition intei'inediate between'tlie Tedipalpi (to which 

 tliey are >omewhat nnnv clos.dy allied) an<l tin- Phalano-i- 

 dea. The Lim-uatulida liaN'e been pla.-ed neai' the mites 

 l).v many rvrvu\ authorities on account of the supposed 

 resemblance of tlieir hii-va^ to sncli sliort-bodied mites 



