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DiscWlSion.-This is a delicate, eyeless species withlong legs. The genus Matta ranges from San Luis Potosi,Mexico, into Brazil. The only other species ofMatta known from caves is M. sboTdonii, which wasdescribed from an eyeless population in Cueva delOjo de Agua de Tlilapan, Veracruz. In a revision ofthe genus, Shear (1978) studied numerous specimensof M. sboTdonii from epigean and cave collectionsand found no significant differences in the genitaliabetween cave and surface populations. Some epigeanspecimens possess reduced lateral eyes. Matta SbOTdoniiis much darker and more robust than is M.mckenziei. In addition to the type-locality M.sbOTdonii is known from caves In Oaxaca, Tamaulipas,and Yucatan.Family TheridiidaeAlthough at least 24 species of theridiid spidershave been reported from caves in Mexico, most havebeen recorded only once and are probably accidentals.Nicholas (1962) lists Spelobion spukilum Chamberlinand Ivie as a troglobite. This species, nowplaced in the genus Thymoites, is probably a troglophile.The genus Achaearanea includes five specieswhich are frequently found in caves and which maybe troglophiles. They are found hanging in webs inMEXICO•GUATEMALA12•,....r·"'.-'"/.//r·Fig. 44.-Distrihution of troglophilic scytodid spiders of the genus Loxosceles: 1, Loxosceles belli; 2, L. bolivari; 3, L.aurea; 4, L. luteola; 5, L. valdosa; 6, L. devia; 7, L. aranea; 8, L. tenango; 9, L. colima; 10, L. misteca; 11, L. tehuana; 12, L.guatemala; unnumbered circles, L. yucatana.156