128 
Psyche 
[June 
specimens taken from the stomach of the cave salamander, Eurycea 
lucifugci. 
The identification of millipeds is founded mostly on the shape of 
the male gonopods, modified legs found on the seventh segment of 
mature males. Classifications have been based on these structures to 
the extent that even some related families cannot be separated if only 
females and immature specimens are available. The gonopods are 
often small and retracted into pockets in the body ; dissection is usually 
necessary to identify species. An attempt is made here to present a 
key to genera based on nonsexual characters that can be observed 
under low magnification. However, adults should be used; adult 
males can be recognized by the prominent reduced and specialized 
legs on the seventh segment, and females have slightly protruding 
genital valves at the base of the second legs (Figs. 2, 8, io). With 
some experience, most specimens can be placed in the appropriate 
genus. Following the key are notes on the described species in each 
genus. The identification of species is still a matter for the specialist, 
most of whom are eager to do such work. Complete references are 
to be found in the checklist of Chamberlin and Hoffman (1958). 
This study was based entirely on specimens, both types and gen- 
eral material, in the Museum of Comparative Zoology. I thank Dr. 
H. W. Levi for his cooperation and help, and Mr. Stewart Peck 
for many unpublished data. 
Key to Genera 
1 a. Adults with no more than 20 segments 
Order POLYDESMIDA, 5. 
ib. Adults with 28 or more segments 2. 
2a. Body of 28 or 30 segments; each segment with six prominent 
macrosetae Order CHORDEUMIDA, 10. 
2b. Body of more than 30 segments; segments without macrosetae, 
or with more than six 3. 
3a. Body segments with elaborate and regular surface sculpturing 
of raised ridges or pyriform lobes; the largest of these bearing 
the pores of the repugnatorial glands (Figs. 1, 2) 4. 
3b. Segments with no more than a few low striations, mostly lat- 
eral; repugnatorial pores inconspicuous (Fig. 14) 
Order JULIDA, Family Nemasomatidae, 20. 
4a. First segment overlapping the head ; gland openings on rounded 
lobes; ocelli usually in a single row, or absent (Fig. 1) 
.. Order SPIROSTREPTIDA, Family Cambalidae, Camhala. 
