1969] 
Shear — Cave Millipeds 
137 
these generic assignments and their names will appear in my forth- 
coming revision of the family. There are numerous epigean species. 
Family Idagonidae Buckett and Gardner 
Genus Idagona Buckett and Gardner 
Idagona westcotti has been described in detail by Buckett and 
Gardner (1967) from material collected in two caves in Clark and 
Butte Counties, Idaho. However, the family is closest to the Cono- 
tylidae, which is completely unrelated to the Cleidogonidae, rather 
than near both these families, as they suggest. The affinities of the 
Conotylidae and related families are primarily Asian, while the 
Cleidogonidae are a uniquely American group. Superficially, mem- 
bers of the Idagonidae cannot be distinguished from conotylids, but 
the outline of a segment (Buckett and Gardner, 1967, Fig. 4) shows 
that Idagona is somewhat deeper-bodied than the sympatric conotylids. 
Family Trichopetalidae Verhoeff 
Two genera, Scoterpes and Zygonopus, are the most modified 
troglobitic millipeds of North America. Causey (1963) gives a key 
to all known genera of the Trichopetalidae. 
Genus Trichopetalum Harger 
Members of this genus seem to have remarkably wide distributions, 
especially for such fragile humus-dwelling animals. Close study of 
geographic variation may show that numerous species are involved. 
Trichopetalum is generally considered troglophilic, though one spe- 
cies, T. subterraneum Causey, is known only from Slack’s Cave, 
Scott Co., Kentucky (Causey, 1967). 
Genus Scoterpes Cope 
Map 4; Fig. 7 
Causey (1960b) has identified 27 taxa in this genus, most of them 
as yet unnamed, presumably differing in details of the male gonopods. 
Because of their small size (to 8 mm) they are frequently overlooked 
by collectors, but are now known to occur in many caves in Mis- 
souri, Illinois, Kentucky, Tennessee, Alabama, and Georgia. Cham- 
berlin and Hoffman list the four described species, of which one 
(S. austrinus Loomis) is illustrated here (Fig. 7). 
Genus Zygonopus Ryder 
Map 4; Fig. 6 
Zygonopus is found in caves in eastern West Virginia (Z. packardi 
