302 CALIFORNIA ACADEMY OF SCIENCES. [Proc. 3D Ser. 



gilliana is apparently concealed under the lateral margin. 

 There are three tubercles instead of five at the base of the 

 abdomen, although there are sometimes traces of another 

 tubercle on either side of the lateral ones. 



The females bear considerable resemblance to Miss 

 Richardson's Dynamene dilatata, but the body is narrower, 

 the epimera smaller and pointed at the sides, and the caudal 

 shield more elongated. 



Dynamene cordata (Richardson). 



Plate XXXIV, Figs. 8-10. 



Cilicisa cordata Richardson, Proc. U. S. Nat. Mus. v. 21, p. 839, fig. 16, 



1899. 

 Dynamene tuberculosa Richardson, /. t. p. 833, fig. 9. 



Male : — Body tapering from behind forwards. Head somewhat produced 

 in the middle, the anterior margin thickened and forming a broad lobe on 

 either side of the prominent rounded frontal projection. Eyes situated on 

 postero-lateral lobes of the head, which are produced backwards. First 

 antennae shorter than the second, the first joint oblong, having an acute 

 process projecting below the small second joint; third joint slender and sub- 

 cylindrical; flagellum 9-12 jointed, reaching beyond the posterior margin of 

 the head. First thoracic segment longer than the succeeding ones, which 

 are of subequal length. Epimera bent abruptly downwards and produced 

 backwards into narrow but rounded points. On the posterior margins of 

 the last few thoracic segments, especially in old specimens, is a transverse 

 row of small double tubercles which increase in size posteriorly. 



First abdominal segment with 5 double tubercles. On the convex base 

 of the large caudal segment is a transverse row of 3 double tubercles, the 

 cusps in the central tubercle situated in a transverse line, those in the lateral 

 tubercles placed the one before the other. The deep median posterior 

 emargination is armed with 3 pairs of teeth, the pair near the apex small; 

 middle pair often double. A prominent tubercle near the apex of the 

 emargination. Inner ramus of the uropods lamellate, concave above, dis- 

 tally acute, and much shorter than the caudal segment; outer ramus large, 

 incurved, expanded on the inner side of the base into a lobe which fits under 

 the inner ramus. The distal portion of the outer margin armed with 4 or 5 

 tubercles; the tip often turned slightly outwards, and extending somewhat 

 beyond the extremity of the caudal segment. 



Length of largest specimen 15 mm. 



Female: — A detailed comparison of the mouth parts, antennae, and other 

 appendages revealed no differences between the forms considered to rep- 

 resent the 2 sexes of this species. The head of the males is a little more 

 produced in front than in the females. The significance of this difference 



