98 Proceedings of the Biological Society of Washington. 



rounded to subrectangular excepting in posterior segments where mod- 

 erately produced. Pores distinctly lateral, present on segments 5, 7, 9, 

 10, 12, 13, 15-19. 



Distinguished especially by the form of the gonopods in the male. 

 These comparatively small and in considerable part concealed. The 

 salient feature is that the telopodite presents only a single, unbranched, 

 slender blade arising from a robust proximal division. In the known 

 species long setae occur along the ectal side of the gonopods, sometimes 

 continuing upon the blade, and there is at the distal end of the proximal 

 division a separate series of stout setae. 



Genotype. — Paradesmns hispidipes. Wood. 



In addition to the genotype, E. simplex, sp. nov. also belongs in this 

 genus. 



Eurymerodesmus simplex, sp. nov. 



This is a smaller and paler species than E. hispidipes (Wood), a form 

 common in some parts of Louisiana and ranging northward to Illinois. 

 The color of the types is fulvous throughout, the dorsum very slightly 

 darkened with the carinse a little paler, without definite median line or 

 other markings. 



Tergites well arched, smooth throughout. 



Head smooth. Vertigial sulcus deep, ending near upper level of antennal 

 sockets. Antennae filiform, the ultimate article alone narrowed; when 

 bent back reaching upon the third tergite. 



Collum strongly bowed forward, the median region of margin more 

 flattened. Posterior margin at middle straight or weakly incurved, 

 laterally bending cephalad of ectad. Lateral ends narrowly rounded. 



In the succeeding tergites the anterior corners of the keels are all well 

 rounded. In the most anterior tergites the caudal margins of the keels 

 run obliquely out forward of ectad, becoming more and more nearly 

 transverse in going caudad, the posterior finally becoming produced 

 usually beginning with the thirteenth or fourteenth tergite, the processes 

 becoming thereafter more and more pronounced to the nineteenth. The 

 lateral margin of keels as seen from above smooth and moderately convex. 

 Last tergite subtriangular, sides a little incurving, tip narrowly truncate, 

 scarcely depressed. Valves with mesal borders thickened, submarginate. 

 Anal scale subtriangular in general outline, but the anterior margin curving 

 caudad at ends and the apex or caudal angle rounded. 



Conical processes between coxae of second legs of sixth segment apically 

 bending caudad. The similar processes between coxa of legs of seventh 

 segment bending forewards against gonopods or near to them. 



Gonopods of the male with the thickened proximal division elongate, 

 moderately clavately thickening distad. Blade short, in length not much 

 exceeding greatest thickness of basal division and equalled or exceeded 

 by the length of the distal setae; arising at ectal edge of base, distally 

 curved a little ectad, slender. 



Length, to near 24 mm.; width, 3.8 mm. 4 mm. 



