NO. 1170. THE FAMILY GOMPHODESMID^— COOK. 715 



eud of the mesial face of the node and is directed cephalad (by flexure 

 ventrad or caiidad) against the side of the compressed proximal part 

 of the structure. 



In Aulodesmus, moreover, the sternum of the sixth segment behind 

 the process is hollowed out to accommodate the cojiulatory legs. This 

 is not accomxilished, as in some cases, by an excavation in the chitiuous 

 exoskeleton, but by the omission of th'at part of it which would inter- 

 fere with the copulatory legs, so that the ventral part of the sixth seg- 

 ment is very short and broadly sinuate posteriorly to a much greater 

 degree than in the two other genera under comparison. 



The segments, including the carinas, are evenly convex dorsally, the 

 most conspicuous irregularity being a distinct, though gradual and not 

 strongly pronounced, i^rominence or rather a general inflation of the 

 surface at the base of the carinse. 



Xotwithstandiug the general similarity in habit between this genus 

 and Astt'odesmus, some difi'ereuces may be pointed out. Aulodesmus is 

 distinctly the larger and heavier of the two, and the dorsum is decidedly 

 more convex when the same sexes are compared, the convexity not 

 being due to a mere difference in the tilt of the cariuit, but resulting 

 from a different curve of the dorsal arch. In Aulodesmus, too, the body 

 is distinctly, though slightly and gradually, narrowed caudad from 

 near the middle, while it is scarcely narrowed anteriorly to the second 

 segment. In Astrodesmus the body is not appreciably narrowed to the 

 ends, which are both very abrupt. 



The small carina at the base of the posterior leg of each segment is 

 much more pronounced than in Astrodesmus. 



The legs of males are distinctly more crassate than in Astrodesmus 

 and their two basal joints especially are densely hirsute, while in Astro- 

 desmus the hairs are comparatively scattering. The copulatory legs of 

 Aulodesmus are also much more densely hirsute and with longer hairs. 



AULODESMUS MOSSAMBICUS (Peters). 

 (Plate LVIII, figs. 2«-2c.) 



Polydesmus mossambicus Peters, Monatsber. d. K. Preuss. Akad.d. Wiss., Berlin, 



1855, p. 81. 

 Eurijdesmua mossambicus Peteks, Reise iiach Mossainbique, Zoologie, 18G2, V, 



p. 533. 

 Aulodesmus mossambicus Cook, Proc. U. S. Nat. Mus., 1895, XVIII, p. 88, pi. iii, figs. 



17,18; pi. VI, tigs. 1-3. 



Vertex without hairs, smooth and shining; sulcus distinct, ending 

 between the sockets in a considerable depression. 



Clypeus smooth and even, except two small and irregular (perhaps 

 accidental) depressions near the middle, and the usual oblique, lateral 

 excavations. 



Antenme sparsely hirsute. 



Gnathochilarium densely hirsute with short hairs. 



