112 ~ DIPLOPODA. 
a. Prozonites* suppressed on the veutral surface, represented 
dorsally by a short shelf which tapers away laterally ; sterna 
extremely narrow, the legs basally almost in contact ; dorsal 
surface convex, with keels nearly or quite vertical; the 
second or the third or the fourth tergal plates laterally 
enlarged ; body capable of being spherically coiled. 
b. Keels of the second segment greatly expanded laterally, 
considerably surpassing in size those of the rest of the 
body; antenne incrassate, with sixth segment much 
shorter than fifth . .- . ..... . . . . Fam. ONISCODESMIDA. 
c. Pectinate rim of terga suppressed ; segments smooth 
with areate posterior portion . . . . . . . . Subfam. OniscopesmMin«&. 
c’. Pectinate rim of terga retained; upper side of terga 
granular or tubercular . . . . . Lo. . Subfam. CyrropEsMIN2. 
. Keels of the second segment very narrow, but the keels 
of the third or of the third and fourth or of the fourth 
and fifth enlarged, much larger than those of the sixth 
and following segments ; antennz not incrassate, the 
sixth segment as long as the fifth. . . . Fam. SPHAARIODESMID. 
d. Keels of the third or of the third and fourth segments 
the largest . . . Subfam. CycLopEsMIN&. 
d’. Keels of the fourth or of the fourth and fifth segments 
the largest . . . . ee ee . . . » . Subfam. SpHa#RiopEsMINA. 
. Prozonites* retained both dorsally and ventr ally as a tubular 
cylindrical prolongation of the metazonite *; keels of the 
anterior segments usually smaller than those of the mid- 
region of the body, rarely those of the second a little 
enlarged ; body capable of being spirally, not spherically, 
coiled. 
e. Antero-lateral border of the first tergal plate produced 
into a horizontally extended lamina which completely 
overlaps the head . . . . . . . . . Fam. PYRGODESMID. 
. Antero-lateral border of the first tergal plate not laminate ; 
the head not concealed. 
f. Lateral and posterior borders of the keels from the 
second at least to the sixteenth segment armed with 
strong setiferous teeth; keels of second larger than 
those that immediately succeed them; antenne 
short, clavate, and widely separated . . . . . . Fam. PERIDONTODESMID. 
* The prozonite is the anterior usually cylindrical portion of the segment which is retractile to a greater 
or less extent within the metazenite of the segment in front; the metazonite being the posterior, leg-bearing, 
usually keeled portion. 
