138 BULLETIN 2 01, UNITED STATES NATIONAL MUSEUM 



Remarks. — The material is very much damaged, but the salient fea- 

 tures of the species can be made out with no doubt of its identity. All 

 the specimens taken are males. 



Tribe LEPTOMYSINI 



Endopods of the third to the eighth thoracic limbs with the carpus 

 and propodus fused and the combined joints divided into a small 

 number of subjoints by vertical articulations ; four posterior pairs of 

 pleopods of the male generally well developed (rudimentary in 

 Mysidetes) ; exopod of the fourth pair of pleopods of the male either 

 elongated or terminating in a thickened spine, while the endopod is 

 always normal ; antennal scale lanceolate and setose all around except 

 in Paramysidetes. 



Remarks. — Fourteen genera have been referred to this tribe, of 

 which Metamysidopsis is described as new in this report. Eight of 

 the genera are represented in the material of this collection. 

 Genus LEPTOMYSIS G. O. Sars 



Leptomysis G. O. Sars, 1S69, p. 333. 



LEPTOMYSIS GRACILIS G. O. Sars 



Leptomysis gracilis G. O. Sars, 1869, p. 333. 



Occurrence. — Bristol Channel, England, identified by G. E. Bullen. 



LEPTOMYSIS MEDITERRANEA G. O. Sars 



Leptomysis mediterranean G. O. Sars, 1877, p. 45, pis. 14-16. 

 Occurrence. — Naples, identified by A. M. Norman. 



Genus MYSIDOPSIS G. O. Sars 

 Mysidopsis G. O. Sars, 1864, p. 249. 



KEY TO THE AMERICAN SPECIES OF MYSIDOPSIS 



a 1 . Antennal scale with an acutely pointed apex acuta (p. 139) 



a 2 . Antennal scale with apex more or less rounded. 



6 1 . Apex of the telson armed with 3 pairs of long strong spines, much longer 



than spines arming lateral margins bigelowi (p. 139) 



b 2 . Spines at apex of telson not specially longer than those arming margin. 



c 1 . Inner uropods without spines inermis (p. 245) 



c 2 . Inner uropods with a row of spines on inner margin extending from 

 statocyst almost to apex. 

 d l . Antennal scale narrowly lanceolate in shape, 9 times as long as broad; 

 lateral margins of telson armed with 25 small, acute spines. 



calif ornica (p. 142) 

 d 2 . Antennal scale oval in shape, 3% times as long as broad; lateral mar- 

 gins of telson armed with 15 to 20 short, stout, blunt spines. 



mortenseni (p. 145) 



