ISOPODS OF NORTH AMERICA. 167 



SO. Genus .^GA Leach. 



Bod}' rather compact. Abclonicn not much narrower than thorax. 



Eyes present, usually hirge, often contiguous. 



First two articles of the peduncle of the first pair of antenna' more 

 or less expanded, dilated. Frontal lamina or epistome laroe. 



Mandibles without molar expansion. Palp of .maxillipeds composed 

 of fiv^e articles." 



Three anterior pairs of leg's with the propodus simple, cTlindrical, 

 not expanded; dact^dus abruptly curved in the middle. Four posterior 

 pairs with the propodus short. 



ANALYTICAL KEY TO THE SPECIES OF THE GENUS .=EGA. 



o. First pair of antennae with the first two articles of the peduncle very much enlarged, 



dilated, flattened. The second article is produced at the upper distal angle in a 



process which extends half the length of the third article. The third article is 



half as wide as the second article, or narrower. Frontal lamina plane or concave. 



b. Terminal segment of abdomen pointed posteriorly, triangulate. 



c. Eyes distant yEga psora ( Linnaeus) 



c^. Eyes contiguous ^Ega antiUens'iH Schio;dte and Meinert 



h'. Terminal segment of abdomen not pointed posteriorly or triangulate. 

 c. Terminal segment bisinuate, forming three obtuse teeth on the posterior mar- 

 gin : . . . jEga ecarinata Richardson 



c^. Terminal segment of abdomen posteriorly emarginate or truncate. 



d. P]yes contiguous ^Ega crenulata Li'itken 



d^. Eyes distant. 



e. Propodus of second and third pairs of legs furnishe<l at distal end on infe- 

 rior margin with linguiform process ^Ega ivehhil (Guerin) 



("'. Propodus of second and third [)airs of legs not furnished at distal end on 



inferior margin with linguiform process .Ega lecont'd (Dana) 



a'. Peduncle of the first pair of antennae with the first two articles not enlarged or 

 dilated, but compressed and rounded. The second article is not produced at 

 the upper distal angle in a process which extends half the length of the third 

 article. Third article not narrower than second article. Frontal lamina con- 

 vex or compressed and elevated. 

 h. Eyes contiguous. 



e. Terminal segment of al)domen whole, entire. 



A'jga tenuipcfi Schicvdte and Meinert 

 c\ Terminal segment of abdomen not whole or entire. 



fl. Terminal segment of abdomen terminating in seven teeth in the middle. 



yEga dentata Schicedte and Meinert 

 d' . Terminal segment of abdomen with small rounded incision or emargina- 



tion at the apex Ega incJua Schicedte and Meinert 



//. Eyes not contiguous. 



c. Terminal segment of abdomen with small, round median nutcli or emargina- 



tioii Ega arctica Liitken 



c\ Terminal segment of abdomen without median notcli or emargination. 

 d. Eyes very large. 



"In drawing the maxillipeds of the various species it was not always possible to 

 l)lace the maxilliped in a position to show all five articles of the palp or to rejjresent 

 the dividiuL' line between the last two articles. 



