ART. 18 NEW GEISTEEA OF MILLIPEDS COOK AND LOOMIS 13 



Family POLYZONIIDAE 



ANALYTICAL KEY TO GENEEA OF POLYZONIIDAE 



Segments strongly depressed, the dorsum nearly horizontal ; segments 20. 



Platyzonium/ 

 Segments strongly convex, 30 to 50 in number. 



Sterna with a broad median groove separating the basal joints of the legs ; head 

 broadly rounded below; antennae and first two pairs of legs distinctly 

 crassate Buzoniiiim, new genus. 



Sterna narrow, the basal joints of the legs nearly in contact ; head nar- 

 rowed below; antennae and first legs slender. 



Body strongly narrowed in front from the fifth segment ; first segment less than 

 half as wide as the body; antennae long, extending beyond the sides of the 

 body, joints 5 and 6 distinctly larger than the others. 



Bdellozonium, new genus. 



Body moderately narrowed in front, the first segment more than half the 

 body width ; antennae short, the joints subequal. 



Last segment covered and exceeded by the large, broadly rounded penultimate 

 segment ; segments 30 Hypozonium, 



Last segment exposed and projecting beyond the distinctly emarginate posterior 

 edge of the penultimate ; segments variable in number, adults commonly with 

 40 to 50 Polyzonium. 



BUZONIUM, new genus 



Type. — Buzomum crmsipes^ a new species from California. 



Diagnosis. — Head subquadrate, the clypeus widened below and 

 the labrum broadly rounded; antennae robust, clavate, uncolored; 

 first two pairs of legs of both sexes distinctly crassate. 



Description. — Body small, moderately convex; body cavity about 

 one and three-quarter times as broad as high. 



Head small, subquadrate, narrowed between the antennae but the 

 clypeus broad and convex and the labrum broadly rounded, the 

 margin denticulate. 



Eyes, two on each side, not prominent nor heavily pigmented, 

 reddish or brownish. 



Antennae not colored, robust, distinctly clavate, joints 5 and 6 

 longer and thicker than the others. 



First segment scarcely half as wide as the broadest diameter of 

 the body, crossed in front above the lateral angles by a distinct ridge 

 from the lower edge of which the thin anterior margin is produced. 



Subsequent segments somewhat polished, marked with fine longi- 

 tudinal striations; dorsum margined by the extended plurae which 

 are visible from above; pore of the fifth segment lower than on the 

 following segments and located on the exposed posterior corner on 

 the anterior subsegment. 



^ Platyzonium is a European genus known only from Spain, originally described as 

 a species of Cryptodesmus. See Cook, O. F., On Cryptodesmus Getschmannil Karsch. 

 Zoologiseher Anzeiger, No. 488. 1895. 



