698 PROCEEDINGS OF THE NATIONAL MUSEUM. 



Sterna without transverse ridges, somewhat excavate mediauly as in 

 Gomphodesmns. 



Sternum of sixth segment of male with a process over twice as long 

 as broad, slightly narrower in the middle and expanded distad where it 

 bears two conical teeth; the distal corners are also somewhat produced 

 into short, rounded processes. 



Sternum of seventh segment medianly deeply and broadly emargi- 

 nate behind the insertion of the copulatory legs, leaving a sharp lami- 

 nate process at the base of each of the normal legs. 



Sternum of the eighth segment 'uith a distinct conic process at the 

 base of each leg of the posterior pair. 



Sternum of fifteenth segment unmodified. 



Sternum of the sixteenth segment with an abrupt median subconic 

 process immediately behind the transverse constriction; this process is 

 directed ventrad. 



Legs of males slender, the anterior scarcely more robust; dorsal sur- 

 face of second joint moderately inflated; legs 1 to G with a distinct 

 fleshy sole, but with claws less reduced than in the larger genera. 



Coxif of second male legs produced into a short oblique cone. 



The copulatory legs of this genus are so constructed as to suggest 

 rather strongly those of Gomphodesmiis, the more striking diflerences 

 being that the node is much more strongly constricted at base, the lat- 

 eral spine at the base of the flagellum is entirely wanting, and the 

 flagella are not recurved or coiled, but merely flexuous; their apices 

 lie between the bases of the copulatory legs. 



The first segment is proportionally somewhat longer medianly, 

 shorter lateially, and with the marginal callus much more strongly 

 developed, than in Astrodesmus; the posterior corner is, however, less 

 strongly developed and the marginal callus not so broad as in Gom- 

 phodesm us. 



In general form and habit the type of this genus lesembles most 

 nearly Astrodesmus, the dorsal convexity being only slightly greater 

 and the cariuiie only slightly more horizontal. Outside of the secondary 

 sexual characters the generic differences are mostly quantitative. The 

 interantennal suture is more distinct, the antennie are more slender, 

 the marginal calli somewhat broader, the penultimate segment shorter, 

 and the projecting portion of the last segment narrower at base. The 

 secondary sexual diflerences are numerous and important, the sternal 

 ridges and the process of the fifteenth segment are absent, the process 

 of the sixth segment is slender, broader at apex, and bidentate or 

 apparently quadridentate, on account of the sharp lateral shoulders; 

 the seventh segment is deeply emarginate medianly behind the copu- 

 latory legs, and with a sharp, flattened tooth on each side at the base 

 of the normal legs; there is a distinct subconical process at the base of 

 each leg of the eleventh pair, the posterior pair of the eighth segment; 

 the sternum of the sixteenth segment has an abrupt process iu front. 



