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list and offered an analysis of our obligative spidersto allow comparison with such animals of othergroups.Recognition of troglobites is not so precise ascould be wished and the certainty of this specialstatus is a matter requiring much more informationthan mere presence of a blind taxon in a cave. Thereare some spiders with attributes of troglobites thatdo not live in caves. Blind spiders are found in termitenests in Africa and others with greatly reducedor obsolete eyes live in ant nests or under moist humusof tropical and temperate forests on many continents.Obsolescence of the eyes is not necessarily ameasure of length of cave life or even indication ofit. A few cavernicoles with essentially normal eyeshave not been taken outside of caves; a prime exampleis Phanetta suhterranea (Emerton), a cavernicolewith small eyes studied by me on specimensfrom 141 caves ranging from Pennsylvania and Illinoissouth into Alabama, with so far no epigeanrecords, but which live deep within caves often underlitter and rocks. This taxon is listed arbitrarily asa troglophile. By contrast, in other instances I haveassumed a more generous attitude in identifyingtroglobites and list a number with degenerated eyesin trivial remnants that are seemingly limited tosingle caves or cave systems. Spider troglobitesshare most of the special features of cave animals ofother groups. The integument is pallid or whitishbecause of loss of pigment and often is less stronglysclerotized than in surface forms. The eyes showvarying degrees of regression from mere loss ofpigment to complete disappearance of all externalvestiges. This occurs in regular pattern in spiderswith loss first of the anterior median pair and thengeneral reduction and gradual disappearance of thethree remaining diads. The troglobite status is rarelyreached without strong modification of the eyes:most of our obligative cavernicoles are eyeless ornearly so. Finally, in spiders and many other groupsthe appendages tend to become long and much thinnerthan in surface forms.Spider troglobites have been derived from cryptozoictaxa of both primitive and specialized groups.Most are sedentary and spin webs in crevices oncave walls and ceilings or in or under detritus on thefloors. Within these webs spiders have minimizedneed for sight and substitute an increasingly keenchemotactic sense centered in the hairs and setae oftheir appendages. Such sedentary types move to newstations only to satisfy food and climate needs. Allof our American spider troglobites and most fromworld centers come from spiders of this type. Thefew hunting spiders that attain troglobite rank havelikewise de-emphasized sight as a life requirement.A prime example is an eyeless troglobitic wolf spider,Adelocosa anops Gertsch, which lives in KoloaCave, Kauai, Hawaii. Also in Hawaii occurs Lycosahowarthi Gertsch, a yellowish, essentially blindtroglobitic species with vestigial eyes, known fromseveral caves.In 1985 Barr and Holsinger published a basic paperentitled "Speciation in Cave Faunas" in which amap was included of the major limestone areas ofthe United States, in which most of our cavernicolespiders are to be found. Spider troglobites are nowknown from the three principle areas as follows: 1.The Appalachian Valley and Western Plateaus; 2.The Texas Region; and 3. The cave areas of CentralCalifornia. Absence of troglobites from variouslimestone nuclei outside of the cited districts reflectsmore than a failure of intensive collecting and indicatesunlikely presence of troglobites. From none ofthe caves in Utah, Idaho, Arizona, and New Mexicohave come spider troglobites in spite of intensivecollecting by arachnologists. Carlsbad Caverns, oneof our great caves, thus far lacks truly derivativetypes. It is likely that additional troglobites may befound in areas south of these three regions but fewwill be found much to the north of the indicatedlimits.Spider Troglobites of AppalachiaWithin this broad province are found manycaves, including such giants as Manunoth and manyothers famous for their faunas. The great wealth ofcave habitats of this region early became an explOrativearea for speleologists who found spidertroglobites relatively numerous: at least 18 are soclaimed and they belong to eight genera of fourfamilies. Especially numerous are taxa of the familiesLinyphiidae and Nesticidae and include 14 ofthe known troglobites. The first known Americanspider troglobite, Anthrobia mammouthia, a smallwhitish spider without trace of eyes, was describedby Tellkampf in 1844 from Manunoth Cave in Kentucky;it is still the only species of its genus. Severaladditional cavernicoles were added by various studentsso that in 1960 Nicholas was able to list ninepresumed obligative taxa from the United States:five of them do not now qualify for that status.American cave spiders are now known from quitelarge collections from many localities, so it is nowpossible to present a favorable picture of our faunaon the basis of new publications and much unpublisheddata in my possession. Our fauna showssimilarity to the European one, with many of the76