276 REPORT OF NEW JERSEY STATE MUSEUM. 



minal segment of abdomen and uropods usually not ciliated. 



A large family, with numerous genera, and all parasitic, 

 mostly on fishes. 



Key to the genera. 



a. Ends of uropods in adults with fringe of setae. .^gathoa. 



aa. Ends of uropods in adults without fringe of setae. 



h. Head not produced behind into three lobes, more or less immersed in 

 first thoracic segment ; front edge of first thoracic segment not trisin- 

 uate. 

 c. Antennae not compressed, not dilated, and first pair widely sep- 

 arated at bases. LIVONEca. 

 cc. Antennae greatly dilated, and first pair contiguous at base. 



CERATOTHOA. 



bh. Head produced behind into three lobes, usually as large median one 

 and two smaller laterally; head not immersed in first thoracic seg- 

 ment ; front edge of first thoracic segment distinctly trisinuate. 



d. Posterior angles of first six segments of body scarcely or not 

 at all prominent, those of seventh segment produced ; epimera 

 of first segments very often almost reach, or not, by short 

 distance, hind angle of segment. olEncira. 



dd. Posterior angles of first segment of body prominent or pro- 

 duced, frequently acute ; hind angles of following segments 

 increase gradually in length, first very often scarcely produced, 

 hind ones, often produced, abruptly longer than first ; epimera 

 of first segments extend beyond hind angles of segment, and 

 hind ones produced, acute. nerocila. 



Genus /CGATHOA Dana. 



Mgathoa Dana, Anier. J. Sci. Art., (2) XIV, 1852, p. 304. Atypic. (Type 

 Mgathoa macro phthalma Dana, Crust. U. S. Expl. Exped., 1852, pp. 

 747, 763. first species.) 



Body elongate, oval. Eyes large, oval, compound. Hind 

 edge of head produced in three lobes. Front edge of first 

 thoracic segment also results in three lobes. Hind lateral angles 

 of thoracic segments not produced. Epimera distinct on all 

 segments of thorax, except first, extend full length of segments, 

 and not acutely produced behind. Abdomen not narrower than 

 thorax, continues outline of body. Segments of abdomen not 

 shorter than last thoracic segments. Pleopods not ciliated. 

 Uropods and terminal segment of abdomen with hairs. 



