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evident in virtually all (nonmonotypic) clades. Inthe kokoweef group, the direction of least to mosttroglomorphic goes from T. deserticola to shoshone.A clearly defined cline is not evident in thebrevistyla subgroup. Although the cavernicolous T.brevistyla has a slightly higher LII/SL ratio, T.jungi has a more reduced AT and female TrIVtubercle count. In the longistyla infragroup,troglomorphy proceeds from the epigean populationof T. longistyla to the troglobitic T. welbourni. Inthe mulaiki infragroup, the direction is from T.hardeni and the species from Marguerite Cave tomulaiki. In the reddelli infragroup, the highesttroglomorphy is in the northernmost populations ofT. reyesi. In the brevidenta infragroup, T. grubbsi isclearly the more troglomorphic of the two species.Finally, the situation in the spinoperca infragroup issomewhat more complex. Although thecavemicolous species clearly form a cline (fromdiplospina to spinoperca, the most troglomorphic),the position of the epigean species is not clear.Contrary to expectation, these species appear moretroglomorphic than the cavernicolous species insome characters (Table 2).Finally, of biogeographic interest is the spatialdistribution of troglomorphy. The resulting pattern(Map 4) is unusually orderly. First, there appears tobe a directionality in troglomorphism. In virtuallyall clades, the least and the most troglomorphicharvestmen are at opposite ends of the clade'sdistribution. Second, and what seems quiteremarkable is that, in virtually all clades, the mosttroglomorphic element is at the N to NE part of thedistribution. The apparent nonrandornness of thesepatterns begs for an explanation. Hopefully one willcome as the distribution patterns ofthe rich Nearcticcavernicole fauna, especially that of central Texas,become better known.~-----'Map 4.-Distribution of troglomorphy in the Texella mulaiki species group. Symbols: open circle = epigean species (and epigeanpopulation of T. longisryla ); black dot = troglobitic species; mixed symbol = troglophilic species (and troglophilic populations of T.longisryla). Arrows give the direction towards increasing troglomorphy; double arrows indicate ambiguity in polarity.170