ISOPODS OF NORTH AMEBICA. 347 



d'. Palp of maxillipedH with four articles. K{)iiu<'ra of second, third, and 

 fourth segments coalesced and perfectly *iniited with the segments; those 

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



(ienus Volidotea Iiit;hardson 

 //. Flagellum of second pair of antennie not multi-articulate. 

 c. Second pair of antenn;e 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 (ienus FAoted Guerin-Meneviile 



(/. Second pair of antenna' nuich longer than the lirst pair. Palp of maxillipeds 

 usually composed of four articles. 

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

 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 Ensiihimcrus Richardson 

 e^. Epimera distinct (.n all the segments of the thorax, including the iirst. 



No lateral sutures at base of al)domen Genus Erichsonelhi BeTiedict 



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

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

 or three articles Genus Cleantis Dana 



57. Genus MESIDOTEA, new genus." 



Palp of maxillipeds composed of live articles. Sides of head cleft, 

 Kyes dorsally situated. Second pair of antenna with a multi-articu- 

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

 exception of the tirst, 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 dactjius reiiexed. Last four pairs of legs aml)ulatory. 



Inner l)ranch of uropoda minute. 



Species large. 



ANALYTICAL KEY TO THE SPECIES OF THE GENUS MESIDOTEA. 



a. Articles of the peduncle of the second antenn?e not dilated; flagellum composed 

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



Eyes present Mesidotea enlomon ( Linnicus ) 



n'. Articles of the peduncle of the second antennte greatly dilated; flagellum com- 

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

 nent. Ej'es absent Mesidotea sabiiii (Kr0yer) 



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

 tofore referred to the genus Ghjptonotus Eights, and more recently to the genus Clnri- 

 d(jle(t Harger. The genus Mesidotea differs from the genus (Ihjptouutiis in liaving the 

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

 separated from the dorsal portion of the segments. In (ibjptonotus the ei)imera are 

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

 Cliiriddtea Harger and Gbiplonotus Eights in having the palp of the maxillipeds 

 composed of five articles instead of three. 



