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uropygids have no frontal gland, whereas one frontalgland is present in schizomids; uropygids havepaired ovaries, but ovaries are unpaired in schizomids;uropygids have 12 esophageal neuromeres,schizomids nine.The Schizomida are currently divided into threefamilies, one of which is extinct. Because the specimensof the extinct family Calcitronidae (from Mioceneor Pliocene deposits in Arizona, U.S.A.) aregenerally in bad condition, character states are hardif not impossible to determine. Rowland (1975a)reviewed the characters and accepted the leg tarsi ashaving 7:5:4:4 segments. The leg tarsi in theUropygi, Hubbardiidae, and Protoschizomidae are7:3:3:3. Because the few specimens of Calcitronidaeknown do not show characters needed to verify theirplacement in the Schizomida (synapomorphies listedabove), an alternate hypothesis can be produced inwhich the. tarsal count 7:3:3:3 is derived in theSchizomida (minus Calcitronidae) and Uropygi. Theplesiomorphic condition is found in the Calcitronidae.In such a scheme the Calcitronidae wouldbecome the sister group and represent an unnamedorder. While Amblypygi have numerous tarsal Isegments (many more than 7), their legs II-IVcounts are like the Schizomida and Uropygi (Shultz,1990). The genus Calcoschizomus (currently placedin Hubbardiidae) is likewise extinct and like themembers of the Calcitronidae the only knownspecimens are not preserved sufficiently well to determinethe character pOlarities. Members of theCalcitronidae and Calcoschizomus will not be mentionedin the following discussion, because of theuncertainty of the characters.Rowland (1975b) in erecting the family Protoschizomidaedid not discuss the phylogenetic relationshipsof the family but from the name of thefamily he clearly indicated he felt it to be moreprimitive than the Hubbardiidae (=Schizomidae). Inhis unpublished dissertation, Rowland (1975a)elaborated on his reasons for considering the Protoschizomidaeto be primitive. He presented severalproposed transformation sequences in which thestructure of the chelicerae and female flagellum wereused to support his hypothesis.The family Protoschizomidae was defined on thebasis of the presence of eight pairs of dorsoventralabdominal muscles, the female flagellum with distinctsegments, the absence of a serrula and brush onthe chelicera, only two teeth on the fixed digit of thechelicera, the presence of "true spines" (see materialsand methods on terminology) on the pedipalp,the symmetrical placement of the spurs of the pedipalp,the ratio of claw and spur lengths to the dorsallength of the pedipalp basitarsus-tarsus, thelength/depth ratio of trochanter IV and femur IV,and the degree of separation of the mesopeltidialplates. Rowland (1975b) did not compare the Protoschizomidaewith the Uropygi, the generally recognizedsister group of the Schizomida.Rowland (1975b) and Rowland and Reddell(1979a) distinguished the genera Agastoschizomusand Protoschizomus on the basis of several ratios:gap between mesopeltidial plates/width of plate,length/width ratio of metapeltidial plates,width/length ratio of stemites IV-VII, length of clawand spurs/dorsal length of pedipalp basitarsus-tarsus.These ratios appeared quite distinctive atthat time since only two small epigean(Protoschizomus) and two large cavernicole(Agastoschizomus) species were known. With thediscovery of several additional cavernicoles(described herein) exhibiting varying degrees of adaptationto the subterranean habitat, the ratios usedto separate the two genera appear to have limitedsignificance at the generic level. We retain the twogenera with greatly different diagnoses based oncharacters apparently unrelated to the degree ofspecialization for cave existence. The following is adiscussion of characters used earlier for separationof the genera and characters which we consider to bemore phylogenetically significant.Cheliceral teeth (character 14): The fixed digit ofthe chelicerae of the Protoschizomidae all have twoteeth with essentially the same shape as in theUropygi. The apomorphic conditions of three andmany more than three teeth are found in the Hubbardiidae.Megaschizominae have three teethwhereas Hubbardiinae have many more than threeteeth.Cheliceral serrula (character 15): The Hubbardiidaepossess a distinct row of hyaline teeth (serrula)on the mesal margin of the movable jaw of thechelicerae which probably function as a cleaning organ.The family Protoschizomidae lacks a true serrula,but does have in the same place a series of smallrounded to sharp knobs or teeth similar in positionand shape to those in the Amblypygi. Uropygidslack teeth. We have recorded the number of teeth inthe serrula, but intraspecific variation in this charactermakes it of limited value even for species recognition.Accessory teeth: Harvey (in press) first noted theimportance of small rounded teeth on the lateralmargins of the movable jaw of the chelicerae andnamed them accessory teeth. Megaschizominae haveseven teeth, whereas Hubbardiinae have 0-3 teeth.Because these teeth are also missing in all protoschi-36