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horizontal passage with a small stream issuing fromit; the third is a large, poorly-explored bat cave,Cueva de Camposantos, which consists of one ormore large chambers. The stream in Cueva de CantilBlanco was inhabited by the snail Melanoides maculata(Born) and an undescribed species of palaemonidshrimp of the genus Macrobrachium. The terrestrialtroglophile fauna consists only of the pholcid spiderPhysoeyclus globosus (Taczanowski) and an undescribedspecies of the scytodid spider genus Loxosceles.The remainder of the fauna consists of accidentalsor bat guano associates.Jalapa, VeracRlz.-This poorly defined and studiedregion consists of the volcanic regions in the generalvicinity of Jalapa, including Cofre de Perote to theeast. Only two caves have been investigated withrespect to their invertebrate fauna. One, Cueva delInfiernillo, is a lava cave entered by a 10-meter deepsinkhole. A single large passage about 200 meters longis now accessible. The cave contains much guano andis not suitable for troglobites. The second cave, Cuevadel Volcancillo, is located on the slopes of Cofre dePerote. The entrance opens onto the wall of thecrater of a subsidiary cone, EI Volcancillo, and extendsfor more than 1,000 meters as a large tube.Numerous caves occur on Cofre de Perote and thearea should prove rich biologically. Two troglobiteshave been identified from Cueva del Volcancillo, anundescribed species of the cleidogonid milliped genusCleidogona and an undescribed carabid beetle of thegenus Para tree hus. The troglophile fauna of theregion includes the amblypygid Paraphrynus aztecus(pocock), a scorpion of the genus Vaejovis, agelenidspiders of the genus Tegenaria, the nesticid spiderEidmannella pallida (Emerton), the pholcid spiderModisimus n. sp., the scytodid spider Loxoscelesn. sp., the cleidogonid milliped Cleidogona n. sp.,campodeid diplurans, and the collembolan Schae!­feria sp.Sierra Madre del Sur SystemAccording to Raisz (1964) the Sierra Madre delSur System includes all of the area between theNeovolcanic Plateau and the Isthmus of Tehuantepec,with the exception of a narrow strip along the PacificOcean and the Gulf Coastal Lowland to the north. Hesubdivides this province into five sections: the Balsas­Mexcala Basin, the Oaxaca Upland, the NortheastFolded Ranges, the Southern Slope, and the NorthernSection. The Southern Slope is a mountainous areaalong the Pacific coast; the Northern Section is thecoastal area in Colima and immediate vicinity. Neitherof these regions has been studied speleologicallyand will not be discussed here.The Balsas-Mexcala Basin is a structurally complexregion largely drained by the Tepalcatepec, Balsas,and Mexcala rivers. It is bounded on the north by theNeovolcanic Plateau, on the northwest by the NorthernSection, on the south by the Southern Slope andon the east by the Oaxaca Upland. The rivers flow atelevations of 300 to 600 meters, while to the souththe land rises to the heights of the Sierra Madre delSur at 2,000 to 3,000 meters. To the east the basinwidens to form a broad plateau dissected by severalrivers. Part of the area is covered by Tertiary volcanics,but Cretaceous limestone is exposed in manyplaces. Along the northern edge of the region, erosionhas removed the overlying volcanic rocks to exposeheavily karsted Cretaceous deposits. This is mostnotably seen in the Cacahuamilpa Region, as discussedbelow. Bonet (1971) has discussed the physiographyand geology of the Cacahuamilpa region, while Fries(1956) has reported on the geology along the highwaybetween Mexico, D. F., and Acapulco, Guerrero.With the exception of the Cacahuamilpa regionthe Balsas-Mexcala Basin has been little studiedspeleologically. Only 17 caves have been examinedfor their invertebrate fauna, but reports on bats inmany parts of the area indicate that it will prove tobe of the greatest interest speleologically. Extensivelimestone deposits, considerable local relief, and highrainfall have contributed to the development of manyextensive cave systems.The Oaxaca Upland is a higher area than the basinto the west and has an overall plateau-like character.To the north it is much dissected and in the centerlies the Valley of Oaxaca. The region is geologicallycomplex with granites, metamorphic rocks, and sedimentarydeposits exposed. Cretaceous limestonecrops out particularly in the southern part of the upland.The area has been little studied speleologicallyand only ten caves have been visited. These are locatedat 1,800 to 2,000 meters elevation in the vicinitiesof San Sebastian and Santiago Apoala.The Northeast Folded Ranges is a disjunct part ofthe Sierra Madre Oriental extending from Cordoba,Veracruz, to Tehuantepec, Oaxaca. It consists largelyof Cretaceous limestone, but volcanic deposits insome areas cover the limestone. The geology of thenorthern part of the area has been discussed by ContrerasV. (1956). This part of Mexico is among themore speleologically important areas in the country.Heavy rainfall, high relief, and massive limestonedeposits have contribute~ to the development ofsome of the more signir;tant caves in Mexico. It isalso one of the better known parts of Mexico withrespect to its invertebrate cave fauna. Among the 10840