300 CALIFORNIA ACADEMY OF SCIENCES. [Proc. 3D Skr. 



be discarded by some writers and retained by others. It 

 is, I believe, a safe rule to follow, to allow a generic name 

 to stand if it differs from the nearest preceding name both 

 in spelling and pronunciation, be this difference ever so 

 little. Dynamene would naturally be pronounced some- 

 what differently from Dynamena, and therefore ought not 

 to be considered a synonym of the latter genus. Whether 

 or not the two words are of the same derivation should not, 

 I believe, be considered. For the purposes of zoological 

 nomenclature a name is a name. If Dynamene is rejected 

 on account of its similarity to Dynamena, new names should 

 be substituted for Dynomene and Dynamina as well. 



It is only after some hesitation that the following species 

 have been referred to Dynamene. The females are con- 

 generic with Dynamene rubra and D. viridis, and as these 

 species are, I believe, members of a vaHd genus, the species 

 here described should also be referred to Dynamene, 

 although the males do not conform to the original definition 

 of Leach. 



Dynamene sculpta sp. no v. 



Plate XXXIV, Figs. 1-7. 



;i/a/^ .• — Body increasing slightly in width posteriorly. Head narrowed 

 and scarcely longer than the first segment of the thorax. Eyes oblong, 

 situated on prominent, rounded, lateral lobes. Thoracic segments minutely 

 roughened behind, the lateral angles produced backwards into subacute, 

 triangular processes; first segment longer than the succeeding ones, the 

 lower side produced forward into a triangular process extending a little in 

 advance of the eye, and backward into a triangular, acute lobe at the postero- 

 inferior angle; last 3 segments with several small setose prominences on the 

 posterior margin. Abdomen large, with 5 segments indicated, the anterior 

 segment marked off by a line extending entirely across the upper surface, 

 the 3 following segments are indicated by 2 pairs of lines which are visible 

 only at the sides; second segment furnished with 3 setose tubercles in a 

 transverse row. Caudal shield large and sculptured, the anterior portion 

 with 3 tubercles, the middle one rather blunt and a little in advance of the 

 others; a pointed tubercle with 2 lateral ridges in front of the posterior notch; 

 notch deep, with a small spine at the end, behind which is a pair of larger 

 spines. Inner branch of the uropods flattened and not nearly reaching the 

 tip of the caudal shield, the tip subacute; outer branch very long, narrow, 

 and incurved, extending considerably behind the tip of the caudal shield and 

 directed obliquely upwards. First antennae a little shorter than the second, 



