468 MTRIAPODA 



ally unpaired and in the hinder part of the body ; the paired ducts leading 



to two openings in the second body segment ; one or both pairs of legs in 



the seventh segment usually modified in structure in the male to serve as 



copulatory organs; the young larvae with but 3 pairs of legs and few 



segments: about 8 families and 125 American species, which are usually 



sluggish animals living under stones and in other dark, moist places, 



and feeding on decaying vegetable and animal matter, but also in some 



cases on living roots and thus often proving destructive in gardens. 



Key to the families of Diplopoda here described : 



Oj Anus in terminal segment ; maxillae forming a plate ; integument hard ; 

 copulatory feet present. 

 6i Mouth parts suctorial and more or less like a proboscis. . . .1. Polyzoniidae 

 6a Mouth parts not suctorial. 

 Ci Segments 30 or more in number, 

 di Both pairs of legs on seventh segment of male copulatory. 

 61 Stink glands present ; anal segment rounded or produced into a spine. 



2. JULIDAE 



€3 Stink glands absent ; anal segment usually elongated into 2 slender 



papillae 3. Craspedosomidae 



dj Anterior pair of legs only on seventh segment of male copulatory. 



4. Lysiopetalidae 

 Cj Segments 20 or 21 ; anterior pair of legs on seventh segment copu- 

 latory 5. POLYDESMIDAE 



»j Anus on the penultimate segment ; maxillae leg-like ; integument soft, 



with bunches of hairs ; copulatory feet absent 6. Polyxenidae 



Family 1. POLYZONIIDAE. 



Body elongate, with a hard integument, and Avide and more or less 

 flattened, consisting of from 30 to 100 or more segments; mouth parts 

 more or less rudimentary and prolonged to form a suctorial proboscis; 

 row of stink glands on each side; both pairs of legs on the seventh 

 segment copulatory : 4 American genera with about 5 species, all of which 

 can roll themselves together so as to form a ball. 



^ POLYZONIUM Brandt. Fi^^st dorsal plate rounded in front and pro- 

 jecting to the base of the antennae, concealing nearly all of the ocelli, 

 which are 2 to 4 in number; antennae close together; legs very short, 

 the third segment being without them: 1 American species. 



P. rosalbum (Cope). Color reddish-brown above, paler posteriorly 

 and along the margins; antennae very dark, with 6 joints; 39 to 53 

 segments: central states, often common. 



Family 2. JULIDAE. 



Body elongate, cylindrical, and with a hard integument, consisting 



of from 30 to 70 segments, the double pairs of legs beginning on the 



fifth ; antennae on the sides of the head ; both pairs of legs on the seventh 



segment of males copulatory; a row of stink glands on each side of the 



