PROCEEDINGS OF THE NATIONAL MUSEUM. 55 



Second legs of male with coxre stout, produced ventrad into a 

 rounded-conic process, in the median face of which is the opening of 

 the seminal duct. 



Male genitalia with the basal joint large and bulbous; second joint 

 very short, with two processes of subequal length, the larger toothed at 

 apex, the smaller simple, needle-like. 



Priodesmus is a type strikingly diflerent from any of the related 

 genera, and although the differences are mostly quantitative, the new 

 form shows, as far as is yet known, the extreme of development and 

 specialization in the line it represents. Indeed, the aspect of the ani- 

 mal is so bizarre and peculiarly different from evidently related genera 

 as to warrant the suspicion that it will be found explainable by some 

 unusual local condition. 



The affinities of this genus are with species described under Rhachido- 

 onorpha, such as R. nodosa, Peters, which appears to be nearer to the 

 present form than to R. iarasca, Saussure, the type of that genus, and 

 may, at least provisionally, stand as a species of Priodesmus. 



PRIODESMUS ACUS,' new species. 

 (Plate I, figs. 1-19.) 



Body oblong, the sides i^arallel, the segments of nearly equal width 

 to near the extremities; dorsum slightly convex, the cariiue horizontal. 



Vertex prominent, especially above; densely granular, without hairs; 

 sulcus deep, extending below the antenna?, but there very iiulistinct. 

 Between the antennie it meets an indistinct sulcus from each antennal 

 socket, the two converging caudad at the point where the vertical sulcus 

 ceases to be distinct. 



Clypens smooth and shining, with a few distinct granules: no hairs, 

 though these may have been rubbed off'. The surface is granular 

 immediately below the antenna?, but smooth farther down and in the 

 middle. 



Antenuiie moderately pilose, the hairs rising from conic granules; 

 length, 5 mm.; joints 2-6 subequal, second joint longest, the sixth much 

 the thickest. 



Mandibulary stipes rather large, the sutures appearing as fine, smooth 

 lines in the granular surface. 



First segment somewhat lenticular in outline; a fine anterior raised 

 margin; traces of four transverse rows of large granules. Lateral 

 edge somewhat irregularly quadridentate, the posterior tooth some- 

 what produced obliquely backward. Somewhat removed from the 

 lateral margin is an oblique sulcus. 



Subsequent segments shorter than the first; large granules in three 

 distinct rows, the third of which is close to the posterior margin; the 

 four marginal teeth more or less distinct, the posterior increasing in 



'The generic name alludes to the coarsely serrate segments; the sjiecific to the 

 slender process of the male genitalia. 



