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caves studied are many large stream caves (particularlyin the Acatlan region of Oaxaca) and some ofthe deeper caves in the world. Extensive karst developmentsouth of Orizaba, Veracruz, and in the Huautlade Jimenez region of Oaxaca has resulted in nearlycomplete internal drainage. Deep, incised river canyonsat the base of these plateau-like regions has providedthe relief necessary for the development ofdeep vertical cave systems, one of which is more than1,000 meters deep. Knowledge of the cave fauna ofthe area, however, is limited to the northern part ofthe mountains. Extensive cave systems have beenreported from the southern part of the ranges butremain unstudied.Colotlipa. Guerrero.-This region is located in easternGuerrero in the vicinity of the town of Colotlipa.The general geology of this part of Guerrero is describedby Fries (1956). The principal limestone unitis the Morelos Formation of Cretaceous age. TheColotlipa region is poorly known and defined andonly Grutas de Juxtlahuaca has been studied. Thislarge cave, now partially developed as a tourist attraction,is famous for its Olmec burials and paintings.The cave is essentially horizontal and contains a smallstream and deep pools. With more than five kilometersof surveyed passage, it is among the longer cavesin Mexico (Roy, 1974).Despite the fact that 35 species, of which four aretroglobites, have been identified from the cave, thefauna remains poorly studied. Several rooms are inhabitedby a large bat population, ten species ofwhich have been identified. The terrestrial troglobitefauna includes the pholcid spider Pholcophora grutaGertsch, the rhachodesmid milliped Pararhachistesamblus Chamberlin, the campodeid dipluran Juxtlacampajuxtlahuacensis Wygodzinsky, and a collembolanof the genus Trogolaphysa. All of these speciesare endemic to Grutas de Juxtlahuaca and are allclosely related to other species in southern Mexicoand Guatemala. Several troglophiles are endemic tothe cave; these include the armadillid isopods Venezilloarticulatus (Mulaik) and V. boneti (Mulaik),the tridenthchoniid pseudoscorpion Tridenchthoniusjuxtlahuaca Chamberlin and Chamberlin, the pholcidspider Physocyclus bicornis Gertsch, the pygrodesmidmilliped llJyrmecodesmus colotlipa (Chamberlin), andthe spirostreptid milliped Orthoporus guerreronus(Chamberlin). Other troglophiles include the annadillidisopod Venezillo cacahuamilpensis (Bilimek),the amblypygid Paraphrynus mexicanus (Bilimek),the scutigerid centipede Scutigera linceci (Wood),the nicoletiid thysanuran Anelpistina boneti (Wygodzinsky),and the carabid beetle Platynus segregatus(Bates). These are all typical elements of the fauna ofsouthern Mexico and many are also reported fromGrutas de Cacahuamilpa.Taxco. Guerrero.-This a poorly defined regionnear the city of Taxco in northern Guerrero. Theprincipal cave-forming limestones in the region arethe Cretaceous Mexcala and Morelos fonnations(Fries, 1956). Although numerous caves are knownfrom reports by zoologists studying bats, only twohave been examined with respect to their invertebratefauna, and neither of these is well known. Spiderswere collected from a small cave on the outskirts ofTaxco, but nothing is known of the cave. The onlyother cave examined is Pozo Melendez, a vertical cavesystem to the south of Taxco. Of eleven species ofinvertebrate reported from the area the only troglophilesof note are the agelenid spider Tegenaria mexicanaRoth, the scytodid spider Loxosceles mistecaGertsch, and the paradoxosomatid milliped Oxidusgracilis (Koch).Cacahuamilpa. Guerrero and Mexico.-This regionis located in northern Guerrero and adjacent Mexicoin Valle de Ixtapan immediately south of the slopesof the volcano Nevada de Toluca. The region isflanked on the east and west by plains of volcanicdeposits and on the south by the Sierra de Tenerias.The geology, speleologenesis, and caves of the areaare discussed in detail by Bonet (1971). This is amongthe more interesting karst regions in Mexico, withseveral large caves known, the most famous of whichis Grutas de Cacahuamilpa. This large horizontalcommercial cave has been known for hundreds ofyears and is described in numerous popular and scientificarticles. Other well-known caves includeGrutas de la Estrella and the two large river caves(Grutas del Rio Chontalcoatlan and Grutas del RioSan Jeronimo) which emerge from two enonnousentrances, collectively called the Dos Bocas, belowGrutas de Cacahuamilpa. The caves of the region areformed in Cretaceous limestone, principally of theMorelos and Mezcala fonnations. Most of the areawas covered by volcanic deposits, but as erosionexposed the underlying limestone karst topographyseveral major streams invaded preexisting cave systemsand now run for several kilometers throughunderground channels.Fourteen caves have been investigated with respectto their invertebrate fauna, but most of the wellknowncaves are large stream passages and not wellsuited to cavernicoles. Additional work in the smaller,drier caves is needed to further elucidate the natureof the fauna of the area. Although 91 species havebeen recorded, only six are troglobites. This paucitymay be due to our limited knowledge of the regionor to the possibility that filling or burial of the caves41