Pacific Coast of North America. 175 



c'. Ultiuiatesegment of abdomen smooth. 

 Outer branch of uropoda but little 

 more than half as long as inner 

 branch. Sinus at extremity of ab- 

 domen small £>. glabra, sp. n. 



It has been suggested by several authors * that Dynamene 

 may prove to be the female of JScesa, but until facts can be 

 produced to substantiate this assumption, it is necessary to 

 retain the genus Dynamene. 



21. Dynamene dilatata, sp. n. 



Body oval; surface very granular; colour yellow. 



Head rugose, with its anterior margin produced in a 

 quadrangular process, having a small median projection, 

 rounded antero-lateral angles, and a thickened edge. First 



Fig. 8. 



Dynamene dilatata. 

 a, head and first thoracic segment, x 13^ ; b, dorsal view, x lOf . 



pair of antennse extend to the posterior margin of the head 

 first two joints flattened and enlarged ; first joint oblono- • 

 second joint triangular, and half as long as preceding joint ; 

 third joint small, as long as second, but half as wide ; tlao-el- 

 lum six-jointed. Second pair of antennae are but little lono-er 

 than first pair and do not reach the posterior margin of the 

 first thoracic segment. 



The thoracic segments are of equal length. The epimera 

 are square or oblong, with straight lateral margins. 



The penultimate abdominal segment is short and crossed 

 v^rith suture-lines. The terminal segment is triangular, with 

 a small rounded notch at the apex. There are three lonoi- 



* Hesse, Ann. Sci. Nat. 5th ser. xvii. pp. 5, 6 ; Stebbing, Hist, of 

 Crust. 1893, p. 361 ; Bate & Westwood, British Sessile-eyed Crust ii 

 p. 432. 



13* 



