NO. 1170. THE FAMILY GOMPHODESMIDJS— COOK. 699 



In Astrodesmus the seventh segment has a median, rounded, flattened 

 expansion behind the copuhitory legs, between the normal pair; there 

 are no conic processes on the eighth segment nor on the sixteenth 

 segment. 



The processes located at the bases of the posterior pair of legs of the 

 eighth segment are narrower and longer than those of Tymhodesm us, 

 the other genus to which the present might be most properly compared, 

 and which has these j^rocesses much more developed than in any of the 

 remaining genera. 



TYCODESMUS MEDIUS Cook. 

 (PlateLVII, figs, la-lc.) 



Tycodesmns viedhis Cook, Proc. U. S. Nat. Mus , 1895, XVIII, p. 83. 



Vertex without hairs, polished and shining; the sulcus distinct, as 

 well as the transverse sulcus connecting the antennal sockets. 



Clypeus with lateral depressions moderate; a transverse row of 

 minute pnnctations above the labrum. 



Guathochilarium densely pilose. 



First segment with i^osterior margins broadly emarginate in the mid- 

 dle and turned ahead laterad ; marginal callus distinct,'the anterior and 

 posterior margins distinct on the cariute. 



Segments dorsally smooth and shining, uneven under a lens, rugulose 

 on the carina? and distinctly inflated at the base of the carina*, as in 

 Aulodesmus; on posterior segments there are faint traces of granules 

 in transverse rows, and the surface of these segments is also more dis- 

 tinctly rugulose. 



Lateral carinse more than one-fourth as wide as the body cavity; 

 marginal callus tapering gradually to the distinct anterior margin; 

 posterior margin very fine or indistinct; posterior corners moderately 

 produced, about as in Astrodesmus stellifer, slightly more on posterior 

 segments; below the carinaB the segments are nearly smooth, the sec- 

 ondary carina very small, but distinct. 



Anterior subsegments smooth and shining, very minutely striolate- 

 rugulose under a high power; transverse constriction distinct, not 

 crenulate. 



Penultimate segment very short, the small dentiform carina exceeded 

 by those of the eighteenth. 



Last segment also very .short, concealed from above by the preceding 

 two; apical projecting portion long, narrow, the apex itself rounded. 



Anal valves striolate-rugulose, the margins weak. 



Preanal scale broadly triangular, apiculate, the setiferous tubercles 

 small, projecting somewhat veutrad, not exceeding the apex; surface 

 nearly smooth. 



Sterna naked except a few hairs along the posterior edge. 



Process of sixth segment hirsute laterad and distad. 



