390 FROCEEDINGS OF THE ACADEMY OF [1897. 



segmental margins. The abdomen is composed of two segments 

 united above but separated at the sides by short incisions. 



In addition to the above generic characters, most species agree in 

 having the head excavated in front, a cross-like areolation between 

 the eyes, the extremities of the cross being usually armed with tuber- 

 cles or spines ; in having a spine or tubercle between the eyes and 

 the front. A deep transverse suture near the back of the head cuts 

 off a postcephalic lobe or areolation ; between this areolation and 

 the cross are two lateral areolations, sometimes united at the base 

 and sometimes separated by a channel. The sides of the thorax in 

 all species show undulations or nodules of more or less prominence. 



The section of the genus of which bicuspida is the type is charac- 

 terized by having the distal end of the abdomen emarginate or bi- 

 cuspid, while in the nodulosa section the end is bluntly pointed. 



The basal plates of the operculum in all species except harfordi 

 are crossed by a diagonal line or ridge. 



SYNIDOTEA Harger. 



Synidotea Harger, American Journal of Science (3), XV, p. 374, 1878. 

 Edotia Miers, Journal Linn. Soc. Lond., XVI, p. 65 (pars), 1 1883. 

 Synidotea G. O. Sars, Norwegian North Atlantic Expedition, Crust., p. 116, 



1885. 



Synidotea Harger, character emended. 



"Antenna? with an articulated flagellum." Epimeral sutures not 

 evident above on the first four segments; on the last three the lines 

 of demarcation are more or less distinct. " Pleon apparently com- 

 posed of two segments, united above but separated at the sides by 

 short incisions. Operculum with a single apical plate. Palpus of 

 maxillipeds three-jointed." 



1 Miers, in his " Revision of the Idoteidre " in this journal, unites several 

 genera under Edotia Guerin-Meneville, then arranges Edotia in three sec- 

 tions as follows : 



# Antenmv well developed, with the flagellum composed of several joints. 

 Postabdomen uniarticulate. (Synidotea). 



'0. Antenna? very small, with the flagellum rudimentary ; postabdomen uni- 

 articulate. (Edotia). 



§§| Flagellum of the antenna; obsolete; postabdomen biarticulate. (Desmares- 

 lia, Epelys. ) 



In this arrangement Professor Sars does not concur, but says in regard to 

 Synidotea, " This genus was first instituted by Harger, and should unquestion- 

 ably be maintained." 



