246 bulletin: museum of comparative zoology. 



210. Strongylosoma semirugosum (Pocock). 

 Ann. mag. nat. hist., 1888, ser. 6, 2, p. 477, pi. 16, fig. d.i 

 Habitat. — Dominica (G. A. Ramage).^ 



211. Lasiodesmus caraibicus Silvestri. 



Bull. Amer. mus. nat. hist., 1908, 24, p. 576, f. IX (1-5). > 

 Habitat.— FoRTO Rico: Utuado (W. M. Wheeler) .^ 



Polydesmidae. 

 Belonodesmus, gen. nov. 



Body composed of head and twenty somites. Antennae long and 

 slender, distally enlarged, the second and fourth articles longest, the 

 sixth somewhat abruptly thickest. 



First tergite narrower than head with mandibles, wider than head 

 without; surface smooth or weakly granular, pilose. Keels well 

 developed, high, marginally elevated, all with strongly produced 

 spiniform caudal angles, these more elevated; laterally serrate and 

 teeth also along caudal margin of most, the teeth setiferous. All 

 tergites excepting the first (cervical) bearing series of tubercles which 

 are more numerous on the middle and caudal ones, the tubercles more 

 or less laterally compressed, elongate and cariniform, setigerous. 

 Excepting first three plates, tergites with a strong transverse sulcus, 

 behind which in most segments there are two rows of tubercles with 

 three or four in front. Prozonites very long, not telescoped in pre- 

 ceding somites, the keels widely separated. 



Anal tergite subtriangular, strongly tubercular. 



Repugnatorial pores opening near the margin of the keels on the 

 dorsal side; occurring on the fifth, seventh, ninth, tenth, twelfth, 

 thirteenth, and fifteenth to nineteenth segments. 



Legs very long. 



In the male gonopods the coxae bear chitinous hooks as usual. The 

 distal division .segmented, the distal or tarsal division branched in 

 type. 



Processes of second coxae in male low. 



Genotype. — B. thaxteri, sp. nov. 



