I3OPODS OF NORTH AMERICA. 299 



SO. Genus DYNAMENE Leach. 



Abdomen composed of two segments, the first of which is formed 

 by the fusion of several coalesced segments. The terminal segment is 

 emarginate posteriori} 7 , without a lobe within the emargination. 



The branches of the uropoda are similar, both being salient; the} 7 

 are alike in the two sexes. The inner immovable branch is fixed to 

 the side of the abdomen. The outer branch is movable and capable 

 of folding under the inner branch. 



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

 are produced into lobes. 



Legs all ambulatory. 



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 

 Cilicsea and Dynamene in a single genus Dynamene, the males of 

 Cilic&a being unlike the females as is the opinion of Prof. S. *I. 

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

 tuberculosa the female of Cilicsea cordata and the latter supposing 

 Dynamene hei^mudensis to be the female of C'dicsea caudata. 



ANALYTICAL KEY TO THE SPECIES OF 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. 



6. Surface of abdomen smooth Dynamene glabra Richardson 



b'. Surface of abdomen with tubercles or longitudinal ridges, 

 o. Surface of abdomen with tubercles. 

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



Dynamene angulata Richardson 

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



Dynamene moorei, new species 

 c f . Surface of abdomen with longitudinal ridges. 



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

 Front of head produced in a quadrangular process. First two articles oi 

 peduncle of the first antenn?e 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 

 antennae not flattened and not greatly dilated. 



Dynamene benedicti Richardson 



DYNAMENE PERFORATA Moore. 



Dynamene per jorata MOORE (male) , Bull. U. S. Fish Commission, XX, Pt. 2, 1902, 

 pp. 173-174, pi. x, figs. 9, 11-19. RICHARDSON (male), Trans. Conn. A cad. 

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



Localities. Culebra, Porto Rico; Bermudas. Found on mangrove 

 roots. 



