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U.S. NATIONAL MUSEUM BULLETIN 292 



the formation. Five days later, the school had apparently disappeared, 

 and far fewer Xiphocaris were to be found in the area. 



Distribution. — Known only from the West Indian islands (Cuba, 

 Jamaica, Hispaniola, Puerto Rico, Saint Croix, Dominica, Saint 

 Lucia I., Barbados). 



Figure 19. — Male second pleopods: a, left, posteromesial view, Potimirim americana 

 (after Smalley, 1963); b, right, mesial view, P. glabra (carapace length 4.2 mm), Dominica 

 station 26; d, right, mesial view, P. mexicana (cl 2.7 mm), near Nequabo, Puerto Rico 

 (H. VV. Harry); ^, right, mesial view, Xiphocaris elongata (fig. 17). Appendices mascu- 

 linae: c, right, lateral view, P. glabra, Dominica;/, left, mesial view, X. elongata, Dominica. 



Dominica Stations: 1-3, 6, 11-15, 17, 30, 36, 38, 44, 48-52, 55, 57, 

 61, 63, 64, 66, 67, 71, 72, 79, 80, 81, 83, 100 (0-1,150 ft.). 



Remarks. — The reason for the variability in the relative length 

 of the rostrum in this species, which led Pocock (1889) to propose, 

 with reservations, three distinct species and a variety, cannot be fully 

 explained by the material collected during the present Dominican 

 Survey. Statistical analysis of this character in the Dominican series 

 demonstrates that growth changes are responsible for some of the 



