722 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.xxi. 



SIGODESMUS, Y\e\r^ genus. 



liody rntlier small, nearly five times as lon^' as broad; dorsum 

 moderately convex, the carina^ decurved nearly in the direction of the 

 dorsal arch. 



Antennic filiform, second joint longest, joints 3 to 5 subequal, dis- 

 tin('tly longer than joint <>; olfactory cones ten. 



First segment less than twice as broad as long, subsemicircular, the 

 antericn- margin being carried around in an even curve to the posterior 

 corner, which is distinctly angled. 



Segments dorsally smooth, rugulose laterad. 



Lateral carinje distinctly margined in front, scarcely so behind; mar- 

 ginal callns distinct, narrowed in front, very narrow on poreless seg- 

 ments, very short and narrow on the first, and passing insensibly into 

 the raised margin; posterior corners of all segments somewhat pro- 

 duced, those of the posterior segments increasingly so, but not as nar- 

 row and S]»iniform as on some of the larger genera. 



Kepugnatorial pores 13, located in distinct excavations facing nearly 

 dorsad. 



Preanal scalerounded triangular, distinctly angled but notapiculate; 

 setiferous tubercles small, distinct, rather close together, not exceeding 

 the apex. 



Sterna with transverse ridges distinct, but not prominent, much as 

 in the smaller species of Astrodesmus. 



Sternum of segment G with a subtriangular process which has a dis- 

 tinct, rounded apiculus; it is slightly shouldered and has a broad base 

 as in Astrodesmus. 



Sternum of segment 7 with posterior rim of copulatory aperture 

 expanded, entire. 



Sternum of segment 15 with a very broadly triangular, small process 

 which fits into a deep excavation in the posterior part of the sternum 

 of segment 14. 



Legs of male moderately crassate, proi)ortionally about as long as in 

 Astrodesmus; dorsal face of second joint much inflated; fleshy sole of 

 first six pairs rather large, the claw much reduced. 



Coxte of second legs of male broadly produced. 



Copulatory legs constructed somewhat as in Astrodesmns, the basal 

 hairy part compressed, not trigonal, narrower and longer than in 

 Astrodesnius; from tlie mesial side of the base of the nodus arise two 

 large spines not present in Astrodesmus; one of these is directed some- 

 what mesad and crosses its fellow while the other is turned laterad ; the 

 flagellum is moderately stout, crosses its fellow, and ends in two stout 

 prongs. 



From Astrodesmus the form of the first segment and copulatory legs 

 render diagnosis easy. The difference in size is also very great, except 

 in the case of A. petilis, from which it is distinct in the more compact 



