230 bulletin: museum of comparative zoology. 



surface of both zones strongly roughened with irregularly branching 

 impressed lines generally coriarious in form, but showing a tendency, 

 especially on the metazonites, for a longitudinal arrangement to 

 prevail. 



Anal scutum with punctations and impressed lines as on other seg- 

 ments; rounded behind, not equalling the valves. Valves with surface 

 similar; mesal borders elevated. 



Of the processes of the anterior legs in the male, the most anterior 

 or those of the third legs are largest, drawn out distally to a slender 

 pointed tip. 



Number of segments, fifty-seven. 



Diameter (male), 4.5 mm. 



655. Zygostrophus alterans, sp. nov. 



Ti'PE.— M. C. Z. 4,796. Paratype.— M. C. Z. 4,797. Queens- 

 land: Toorwary near Brisbane (W. M. Wheeler). 



In the character of its gonopods approaching Z. dig'xtulus (Brole- 

 mann) more nearly than jcrrugijiopcs, the genotype. The median 

 plate has the sides more evenly curving; it is distally more prolonged 

 and the tip is set off as a more slender process which equals or slightly 

 surpasses the processes of the coxal plates. The narrowing distad 

 of the coxal plate of the anterior gonopods is much less abrupt than 

 in Z. digitulus. The distal part of the telopodite is broad, angular 

 at apex and with an angular ectal projection nearly as in Z. digitulus. 



The general color is blue-black with the caudal borders of meta- 

 zonites red; small black spots over part of the pores, labial border 

 fulvous. Antennae and legs bright ferruginous. 



Head with sulcus, eyes, and antennae nearly as in Z. ferruginopcs. 



Collum of male differing from that of the genotype in having the 

 lower angle more acute, the lower margin evenly continuous with the 

 anterior one. 



In the anterior region the segments are much as in the genotype, 

 with transverse striae similarly developed but surface in general less 

 roughened. On some of the anterior segments the prozonites are 

 marked with curved crescentic to horseshoe-shaped marks which 

 become smaller caudally, passing into small punctiform impressions. 

 In the posterior region the segments above almost wholly smooth. 



The network of impressed lines on anal segment very fine and 

 obscure. Scutum rounded, not surpassing the valves. The latter 

 with mesal margins elevated. 



