PROCEEDINGS OF THE NATIONAL MUSEUM. 99 



ANALYTICAL KEY TO THE GENERA OF OXYDESMID^. 



Dorsum densely beset with several (5 to 6) transverse rows of coarse granules: 

 Geuus Scytodesmus, type S, kribi, Berlin Museum. 



Dorsum nearly smooth, finely granular, or with three rows of polygonal areas, 

 each with a large tubercle or granule in the middle 



First three or four segments with one or more large tubercles or processes from 

 the middle of the posterior margin : Genus Orodesmus, type 0. forceps, British 

 Museum. 



Granules of third and fourth segments, if present, not conspicuously enlarged or 

 coalesced into a process 



Posterior subsegmeuts faintly rugulose, apparently smooth and shining; no 

 tubercles or granules; no trace of a transverse furrow: Genus Mimodesmus, type M. 

 paraUelus, Berlin Museum. 



Posterior subsegmeuts either tuberculate or granulate, and with a distinct trans- 

 verse furrow 



Apex of last segment broad, rounded, faintly emargiuate, not exceeded by mar- 

 ginal tubercles : Genus Oxydesmus, type 0. Jlavomarginatus, Berlin Museum. 



Apex of last segment narrow, included in a distinct sinus between the posterior 

 pair of marginal tubercles 



Carinte not distinctly margined, the pores located in a distinct depression, not in 

 a bead-like, poriferous marginal callus: Genus Isodesmus, type I. immarginatus. 



Carinas distinctly margined, especially cephalad, and with a bead-like, poriferous 

 marginal callus 



Fourth segment slightly, though distinctly, narrower than the third and fifth; 

 cariniB coarsely dentate along the posterior margin, somewhat areate dorsally: 

 Genus Anisodesmus, type A. ccrasinns. 



Fourth segment equal to the others ; carina) entire, not areate : Geuus Tylodesmus, 

 type T. crassipes. 



ORODESMUS,' new genus. 

 Oxydesmus, pro parte, of Karsh and Porat. 



Diagnosis. — Body moderately large. 



Anteuute with four olfactory cones. 



Segiiieiits dorsally granular-rugose, with three transverse rows of 

 tubercles. 



Segments 1-4 with some of the middle tubercles hypertrophied. 



Lateral carin;^ large, thin, more or less dentate at the lateral edge. 



Eepugnatorial pores 11, dorsal on the outer slope of the intra- 

 marginal ridge of segments 5, 7, 9, 10, 12, 13, 15-19. 



Penultimate segment exceeding segment IS. 



Last segment broad, subquadrate, the apex strongly dentate; supe- 

 rior lateral tubercle very large. 



Sterna without spines, ridges, or processes. 



Male legs somewhat crassate. 



Male genitalia not flexed, free. 



' The name alludes to the dorsal prominences. 



