474 STALK-EYED CRUSTACEA 



Synopsis of the Genera. 



I. The first abdominal segment overlaps the posterior 

 lateral margins of the carapace. 



A. The projection in the median line on the posterior 

 border of the abdominal segments are short. Outer mar- 

 gin of basal antennal scale is smooth. — {Acauthephjra). 



Oplophonis. 



B. The projections in the middle line on the posterior 

 border of the abdominal segments very long. Outer 

 margin of basal antennal scale has teeth. — {Oplophorus). 



C. The posterior border of the abdominal segments 

 has a subequal small tooth on each 

 side of the median line. Outer margin 

 of basal antennal scale smooth, an- 

 terior margin rounded. — {Gonatonotus). Gonatonotus. 



I. Acanthephyra. 



Acaiithephyra . A. Milne Edwards, Smith, Spence 

 Bate. 



The dorsal crest extends from rostrum to telson. 

 Carapace anteriorly produced into a long, slender rostrum 

 having a number of teeth above and below. Frontal 

 margin depressed, and excavated to form an orbit, the 

 outer canthus being defined by a rounded angle, external 

 to which stands the internal antennal tooth, then a second 

 excavation is formed to receive the external antenna;, 

 at the lower angle of which the second antennal tooth 

 projects. The first segment of the abdomen is as deep 



