ISOPODS OF NORTH AMERICA. 167 



SO. Genus ^EGA Leach. 



Body rather compact. Abdomen not much narrower than thorax. 



Eyes present, usually large, often contiguous. 



First two articles of the peduncle of the first pair of antennae more 

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



Mandibles without molar expansion. Palp of maxillipeds composed 

 of five articles. a 



Three anterior pairs of legs with the propodus simple, cylindrical, 

 not expanded; dactylus abruptly curved in the middle. Four posterior 

 pairs with the propodus short. 



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



a. First pair of antenme 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 sEga psora (Linnaeus) 



(/. Eyes contiguous JKga antillensis Schioedte and Meinert 



b'. 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. Eyes contiguous ^Ega crenulata Liitken 



d' '. Eyes distant. 



e. Propodus of second and third pairs of legs furnished at distal end on infe- 

 rior margin with linguiform process &ga webbii (Guerin) 



e' '. Propodus of second and third pairs of legs not furnished at distal end on 



inferior margin with linguiform process ^Ega lecontii ( 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. 

 b. Eyes contiguous. 

 c. Terminal segment of abdomen whole, entire. 



^Ega tenuipes Schioedte and Meinert 

 c'. Terminal segment of abdomen not whole or entire. 

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



j-Kga dentala Schiosdte and Meinert 

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



tion at the apex jEga incisa Schioedte and Meinert 



b'. Eyes not contiguous, 

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



tion JKga arctica Liitken 



c'. Terminal segment of abdomen without median notch or emargination. 

 d. Eyes very large. 



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

 place the maxilliped in a position to show all five articles of the palp or to represent 

 the dividing line between the last two articles. 



