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PACIFIC SCIENCE, VoL XII, April, 1958 
of the salps on cruise 8, 158° W., appeared to 
be unrelated to upwelling, however. There 
appears to have been an influence of island 
proximity on salp abundance on cruise 5, 158° 
and 172° W. It apparently had no effect on 
the abundance at either longitude of cruise 8. 
The influence of shearing at current margins 
apparently affected salp abundance on cruise 
5, 158° W., and cruise 8, 158° W. Other than 
these, no relationships of salps to ecologic 
factors can be determined from the available 
data. 
Relative Abundance of Species 
The most numerous species of salp in the 
POFI collections is Thalia democratica. In the 
central Pacific Ocean, therefore, the statement 
of Apstein (1906) that this species is the com- 
monest salp in warm water holds true. Simi- 
larly, in the East Indies (Ihle, 1910), the 
Philippines (Metcalf, 1918), the Great Barrier 
Reef lagoon (Russell and Colman, 1935), and 
southeast Australia (Thompson, 1948), T. 
democratica is the commonest species found. 
However, it was reported by Ritter (1905) as 
Fig. 5. Cruise 8, 158° W. longitude, a. Relationship of total salp volume, total salp numbers, and numbers of 
Thalia democratica to major currents, upwelling, and island masses. Limits of currents, upwelling, and islands are 
approximate, h , Relationship of the other common species, Salpa fusiformis , Ritteriella amboinensis , and Cyclosalpa 
pinnata to major factors listed in a. 
