12 
John R. Holsinger and David C. Culver 
such as springs and seeps, were sampled occasionally in order to obtain 
specimens for comparison with those taken from nearby caves. 
The species covered in this study are essentially macroscopic forms 
(i.e., generally larger than 1 mm). Microscopic forms (< 1 mm) that are 
sometimes reported from cave waters (e.g., protozoans, rotifers; see 
Gittleson and Hoover 1970) or from the interstices of sand and gravel 
substrates beneath cave streams (e.g., tiny oligochaeates, copepods, ostra- 
cods) have not been included. Some preliminary studies, however, on 
polluted pools in Banners Corner Cave in Russell County (see Holsinger 
1966) and the interstitial habitat beneath a stream in Buis Saltpetre 
Cave in Claiborne County (unpubl. data) indicate a potential richness of 
subterranean microscopic organisms that would be profitable to investi- 
gate in a future study. 
Although our study does not cover all of the Clinch Valley in Ten- 
nessee (Fig. 2), some pertinent data on the distribution of species 
recorded from caves just southwest of the study area in Anderson 
County are included. These data add significant details to the picture of 
the geographic distribution of species or species groups whose ranges 
extend into parts of the Clinch basin outside the study area. Moreover, 
except for a few major caves in Hawkins and Sullivan counties, which 
lie just south of the Tennessee-Virginia border, our survey does not 
cover the Holston Valley in eastern Tennessee (see Fig. 1, 2). 
Definition of Terms 
Cavernicoles are usually classified ecologically according to their 
level of adaptation and degree of restriction to the cave environment. 
The commonly accepted system, which is used throughout this paper, is 
defined as follows (see also Barr 1963, 1968). (1) Troglobites are obliga- 
tory species, which are restricted to caves or similar habitats. Morpho- 
logical modifications (specializations) called troglomorphisms usually 
distinguish troglobites and may include, among other things, loss or 
rudimentation of eyes and pigment, and attenuation of the body, 
appendages, or sensory hairs. (2) Troglophiles are facultative species, 
which are able to complete their life cycle within a cave but may also 
occur in ecologically suitable habitats outside caves. (3) Trogloxenes are 
species habitually found in caves or similar cool, dark habitats outside 
caves, but they must return periodically to the surface or at least to the 
entrance zone of a cave for food. Some species, however, such as certain 
cave crickets, may be trogloxenic under one set of circumstances and 
troglophilic under another (see Barr 1963). (4) Accidentals are species 
that wander, fall, or are washed into caves and generally exist there 
temporarily. 
Many small aquatic invertebrates (e.g., flatworms, crustaceans) 
simultaneously inhabit both caves and subterranean groundwater habitats 
