A REVIEW OF THE MYSIDACEA 223 



KEY TO THE SPECIES OF MYSIDIUM 



a 1 . Apex of telson evenly rounded, neither incised nor emarginate; spines on 

 lateral margins, including the apex, about 35 on each half; antennal scale 



5 times as long as broad integrum (p. 223) 



a 2 . Apex of telson incised or emarginate. 



6 1 . Telson incised at apex; spines on telson, including the incision, 23 on each 



half; antennal scale 7 times as long as broad columbiae (p. 223) 



b 2 . Apex of telson emarginate; spines on telson, including the emarginate, 25 

 on each half; antennal scale 4 times as long as broad gracile (p. 223) 



MYSIDIUM COLUMBIAE (Zimmer) 



Diamysis columbiae Zimmeb, 1915b, p. 172, figs. 23-29. 

 Mysidia columbiae Zimmeb, 1918, p. 26. 



Occurrence. — Venezuela : Puerto Cabello, January 1892, collected 

 by K. Levinsen, 24 females, 13 males. Virgin Islands: St. Croix, 

 February 19, 1906, 4 fathoms, 1 male, 1 female. 



Distribution. — Previously known only from Cartagena, Colombia, 

 where the type specimens were collected, the range now includes Vene- 

 zuela and the Virgin Islands. 



MYSIDIUM GRACILE (Dana) 



Macromysis gracilis Dana, 1852b, p. 653 ; 1855, pi. 43, figs. 5a-m. 

 Mysidium gracile Czekniavsky, 1887, p. 85. 

 Mysidia gracilis Zimmek, 1918, p. 24. 



Occurrence. — Virgin Islands: St. Croix, February 19, 1906, 4 

 fathoms, 1 female. 



Distribution. — Known previously only from the harbor of Rio de 

 Janeiro, the Virgin Islands are now included in the range. 



MYSIDIUM INTEGRUM, new species 



Figure 96 



Description. — Carapace short, leaving the last two thoracic somites 

 exposed in the middorsal line, front margin only slightly produced as 

 a rostral plate, which is broadly triangular, with a blunt apex, not 

 covering the eyestalks. 



Eyes large and globose, pigment light brown. 



Antennal scale (fig. 96, a) five times as long as broad, extending 

 only slightly beyond the antennular peduncle, setose all around, with 

 a distinct distal joint and a prominent spine on the outer corner of 

 the joint from which it arises; antennal peduncle very short, less than 

 half as long as the scale and composed of three short more or less equal 

 joints. 



The mouth appendages and thoracic limbs resemble closely those of 

 M. gracile as described and figured by Zimmer (1918). The sixth 

 joint of the endopods of the third to the seventh thoracic limbs (fig. 



