BULLETIN 54, UNITED STATES NATIONAL MUSEUM. 

 33. Genus v<EGATHOA Dana. 



s large, oval, composite. Posterior margin of head produced in 

 three lobes. 



Anterior margin of first thoracic segment manifestly trisinuate. 

 Post-lateral angles of thoracic segments not produced. Epimera dis- 

 tinct on all the segments of the thorax with the exception of the first; 

 they extend the full length of the segments and are not acutely pro- 

 duced posteriorly. 



The abdomen is not narrower than the thorax, but continues the 

 oval outline of the body. The abdominal segments are not shorter 

 than the last thoracic segments. Pleopods not ciliated. Uropoda arid 

 terminal segment of abdomen furnished with hairs. 



ANALYTICAL KEY TO THE SPECIES OF THE GENUS ^EGATHOA. 



a. Frontal margin of head produced anteriorly in a median lingulate projection. 



jEgalhoa linguifrons Richardson 



a' . Frontal margin of head not produced anteriorly in a median lingulate projection. 

 b. Surface of head smooth, evenly convex. Second pair of antennae composed of 

 ten articles. First thoracic segment longer than any of the succeeding seg- 

 ments, which are of equal length Jfyathoa oculala (Say) 



V . Surface of head with central portion sharply raised above the lateral portion, 

 which is deeply excavate just in front of the eyes. Second pair of antennae 

 composed of eight articles. First three thoracic segments of equal length; 

 last four subequal and somewhat shorter than first three. 



jEgathoa medialis Richardson 



jEGATHOA LINGUIFRONS Richardson. 



jEgalhoa linguifrons RICHARDSON, Proc. U. S. Nat. Mus., XXIII, 1901, p. 526. 

 Locality\ Trinidad. 

 Body narrow, elongate; abdomen not narrower than thorax. 



Head with sides rounded. Frontal margin ab- 

 ruptly produced anteriorly into a median lingulate 

 projection, with apex rounded; posterior part of pro- 

 jection forming a raised surface sharply defined on 

 anterior part of head, extending back to eyes. Eyes 

 large, oval, occupying two-thirds the width of head. 

 First pair of antennse nine-jointed. Second pair 

 more slender equal in length to first pair and ten- 

 jointed. 



First three thoracic segments long, second one 

 shortest; last four segments short, of nearly equal 

 FIG. 2i8.-^GATHoA 1^^ All the abdominal segments distinct; first 



' . ' 



five equal in length, terminal segment rounded at 

 apex. Uropoda longer than terminal segment. Inner branch obliquely 



This genus, perhaps, represents the young of Livoneca. The figure given by 

 Schioedte and Meinert of the young female of Livoneca redmanni does not apparently 

 differ from sEgathoa oculatn (Say). I have not suppressed the genus, however, 

 because I could not be positive of the identity of these forms. 



