ISOPODS OF NORTH AMERICA. 347 



d / . Palp of maxillipeds with four articles. Epimera of second, third, and 

 fourth segments coalesced and perfectly united with the segments; those 

 of the fifth, sixth, and seventh segments distinct and well developed. 



Genus Colidotea Richardson 



V. Flagellum of second pair of antennae not multi-articulate, 

 c. Second pair of antennae shorter than the first pair. Flagellum rudimentary 

 Epimera of all the segments united with the segments. Abdomen com- 

 posed of a single segment, with lateral incisions near the base. Maxillipeds 



with a palp of three articles Genus Edotea Guerin-Meneville 



</. Second pair of antenme much longer than the first pair. Palp of maxillipeds 



usually composed of four articles. 

 d. Abdomen consisting of a single segment. Flagellum of second antennae 



consolidated to form a single clavate article. 



e. Epimera of all the segments united with the segments except the last 

 two, which are well developed and distinct. Lateral sutures at base of 

 abdomen indicate another partly coalesced segment. 



Genus Eusymmerus Richardson 

 ef '. Epimera distinct on all the segments of the thorax, including the first. 



No lateral sutures atlbase of abdomen Genus Ericfisonella Benedict 



d f . Abdomen consisting of more than one segment. Flagellum of second pair 

 of antennae consolidated to form a single article or composed of only two 

 or three articles Genus Cleantis Dana 



37. Genus MESIDOTEA, new genus. 



Palp of maxillipeds composed of five articles. Sides of head cleft. 

 Eyes dorsally situated. Second pair of antennae with a multi-articu- 

 late flagellum. Epimera of all the segments of the thorax, with the 

 exception of the first, distinctly separated from the segments. 



Abdomen composed of four segments, with suture lines at the base 

 of the fourth or terminal segment indicating another partly coalesced 

 segment. First three pairs of legs prehensile, with propodus dilated 

 and dactylus reflexed. Last four pairs of legs ambulatory. 



Inner branch of uropoda minute. 



Species large. 



ANALYTICAL KEY TO THE SPECIES OF THE GENUS MESIDOTEA. 



a. Articles of the peduncle of the second antennae not dilated; flagellum composed 

 of from eight to fourteen articles. Antero-lateral cervical lobes prominent. 



Eyes present Mesidotea entomon ( Linnaeus) 



a'. Articles of the peduncle of the second antennae greatly dilated; flagellum com- 

 posed of from seven to eight articles. Antero-lateral cervical lobes not promi- 

 nent. Eyes absent Mesidotea sabini ( Kr0yer ) 



This genus is proposed for the two forms, entomon and sabini, which have been here- 

 tofore referred to the genus Glyptonotus Eights, and more recently to the genus Chiri- 

 dotea Harger. The genus Mesidotea differs from the genus Glyptonotus in having the 

 epimera of all the segments of the thorax, with the exception of the first, distinctly 

 separated from the dorsal portion of the segments. In Glyptonotus the epimera are 

 separated on the last three segments only. The new genus differs from both 

 Chiridotea Harger and Glyptonotus Eights in having the palp of the maxillipeds 

 composed of five articles instead of three. 



