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legs than expected (2.6-3.2). This character is themost sensitive indicator of troglomorphy, apparentlydiscriminating between epigean and cavemicolouspopulations of the same species. In T. bifurcata, thecavemicolous specimen has a higher LIIISL value(3.3) than the epigean specimens (2.6-3.1) and in T.longistyla, the epigean specimen has a lower LIIISLvalue (2.8) than the cavemicole specimens(3.5-3.6).Another character, related to leg length, is thetarsal count (TC). As discussed earlier, a low TC(3-5-4-5) appears to be plesiomorphic in Texella andan increased TC (3-5-5-5) is most parsimoniouslyinterpreted as a synapomorphy for the mulaiki subgroup.However, further increases in the number oftarsomeres appear to be troglomorphic. In fourspecies of troglobites, the mulaiki infragroup and T.reyesi, the TC is distinctly higher (as well as beingpolymorphic); the remaining troglobite, T. welboumi,shows no increase in TC.Also related to appendage elongation is the attenuationof palpal elements, including palpalmegaspines, present only in the most troglomorphicspecies, the mulaiki infragroup.2) Eye reduction. All epigean species and mostcavernicoles have well developed eyes. The fivetroglobitic species lack a retina; four of these alsolack all traces of a cornea. In T. reyesi the conditionof the cornea varies from being well developed tocompletely absent. Retinal loss thus precedes cornealloss as appears to be the case in all other Phalangodidae.The reduction of the eye mound seems to be thefinal step in this transformation series (at least in13'~5 11 : 146\ \ ••1-153~•••r·"" 9 16• • •4/ \ I7 8/10 \ -- ./18/•17Map 2.-Map of western Texas and southeastern New Mexico showing distribution of the species of the Texella mu/aiki group.Numbers: I, T. /ongisry/a; 2, T. we/bourni; 3, T. jungi; 4, T. brevisry/a; 5, T. bi/obara; 6, T. hardeni (I-laby Salamander Cave, only);7, Marguerite Cave; 8, T. cokendo/pheri JRobber Baron Cave, only); 9, T. mu/aiki; 10, T. brevidenta; 11, T. gmbbsi; 12, T. redde/li;13, T. reyesi; 14, T.. spinoperca; 15, T. dip/ospina; 16, T. renkesi; 17, T.fendi; 18, T. homi.167