ISOI'ODS OF NORTH AMP^RICA. 299 



SO. Genus DYNAMENE Leach. 



Abdomen eompo.sed of two scoiiKMits, the Hr.st of whicli i.s forniod 

 by the fusion of several coalesced setiiueiits, The teniiirial segment is 

 emarginate posteriorly, without a lobe within the emargination. 



The branches of the uropoda are similar, both being salient; they 

 are alike in the two .sexes. Tlu^ iiuuM" immovable branch is fixed to 

 the side of th(» abdomen. Vho outer hi-audi is movable and capable 

 of folding under tiie inuei- branch. 



The second, third, and fourth articles of the palp of the maxillipeds 

 are produced into lobes. 



Legs all ambulator3^ 



Sexes alike. 



Inasmuch as the male is known in four of the species of this genus 

 and as the male and female are alike, I am not willing to unite 

 Oiliara and Di/iiamene in a single genus Dynamene, the males of 

 Cilicxa being unlike the females as is the opinion of Prof. S. A. 

 Holmes and Dr. H. F. Moore, the former considering Dynamene 

 tuhevculom the female of C'll'icxa cordata and the latter supposing 

 Dynamene herTnudensis to be the female of Cllic^^a caudata. 



ANALYTICAL KEY TO TIIE SPECIES OP THE GENUS DYNAMENE. 



a. Posterior extremity of terminal segment of abdomen with a heart-shaped opening 



immediately above the terminal excavation Dynamene perforata Moore 



a'. Posterior extremity of terminal segment of abdomen without heart-shaped open- 

 ing above the terminal excavation. 



b. Surface of abdomen smooth Dynamene glabra Richardson 



//. Surface of abdomen with tulu'rcles or longitudinal ridges, 

 r. Surface of al)domeii with tubercles. 



d. Basal part of terminal segment of abdomen with three tubercles. 



Dynamene anyuhtta Richardson 

 d' . Basal part of terminal segment of abdomen with four small tubercles. 



Dynamene moorel, new species 

 c'. Surface of abdomen with longitudinal ridges. 



d. Surface of terminal segment of abdomen with three longitudinal ridges. 

 Front of liead i>roduced in a (|uadrangnlar process. First two articles ol 

 peduncle of the first antenna' flattened and dilated. 



Dynamene dilatata Richardson 

 d^. Surface of terminal segment oi abdomen with four longitudinal ridges. 

 Front of head not produced. First two articles of peduncle of second 

 antenna' not flattened and not greatly dilated. 



Dynamene benedicti Richardson 



DYNAMENE PERFORATA Moore. 



Dynamene 'perforata Mooke (male), Bull. U. S. Fish Commission, XX, Pt. 2, 1902, 

 pp. 173-174, pi. X, figs. 9, 11-19. — Richardson (male). Trans. Conn. Acad. 

 Sci., XI, 1902, pp. 291-292, pi. xxxi.x, fig. 39. 



Localitlefi. — Culebra, Porto Kico; Bermudas. Found on mangrove 

 roots. 



