184 S. 1. Scudder—Structure and affinities of 
bristling all over with a coarse tangle of thorny spines, and 
the smooth galley-worm of the present da: 
f we pass to the ventral plates we shall find differences of 
even greater significance. In modern Diplopoda these plates 
are minute; the anterior forms the anterior edge of the seg- 
ment, continuous with that of the dorsal plate; together, how- 
ever, they are not so long as the dorsal plate at their side, and 
the latter appears partly to encircle the posterior of the ventral 
plates by extending inward toward the coxal cavities. The 
legs are attached to the posterior edge of each ventral plate, 
and those of opposite sides are so closely crowded together that 
they absolutely touch. The stigmata, of which there is a pair 
to each ventral plate, are placed at the outer edge, rather 
toward the front margin, and their openings are longitudinal, 
i. e., they lie athwart the segment; the cox of the legs of the 
anterior plate are therefore opposite the stigmata of the poste 
rior plate. No other organs are found upon the ventral plates; 
one might indeed say there was not room for them. The legs 
themselves are composed of six simple, cylindrical joints, sub- 
equal in length, the apical armed with a single terminal claw ; 
the whole leg is short, generally not more than half as long as 
the diameter of the body. 
the diameter of the body, and sometimes nearly twice as long 
moreover they are not cylindrical but compressed and slightly 
