FISHERY BULLETIN: VOL. 71, NO. 4 



60° 



100° 



Figure 20. — Geographical distribution of Encahimis siihiciutis. Localities shown based on records verified by analysis 



of integumenlal organs. 



other morphological features of subteiiuis ex- 

 cept to confirm that in virtually all specimens 

 from each ocean the mandibular basis bore 

 three setae as found by Fukase (1957). 



The data were first examined by pooling the 

 samples from each ocean and comparing the 

 mean number of perforations between oceans. 

 Differences between the pooled samples proved 

 to be highly significant (Table 6), and the mean 

 PN values show a pronounced geographical 

 trend. The lowest mean was obtained from the 

 Pacific Ocean specimens and the highest from 

 the Atlantic Ocean specimens. The pooled sam- 

 ple from the Indian Ocean yielded a mean PN 

 virtually midway between the other two. 



The gross indication of clinal variation 

 suggested further consideration at a finer scale. 



The PN counts of subteiiuis were regrouped 

 by geographical source of the specimens in units 

 of 60° of longitude and compared in terms of 

 frequency distribution and mean PN per geo- 

 graphical segment (Figure 21). Grouped sam- 

 ples falling within the hydrographic limits of 

 any one ocean do not differ significantly (Table 

 7) and serve to emphasize the stepped or dis- 

 continuous pattern of the means from the dif- 

 ferent oceans. The range shown by PN in the 

 two geographical segments between long. 30° E 

 and 150°E (Indian Ocean and westernmost 

 Pacific Ocean) spans the apparent differences 

 in the distribution of PN in the Pacific and 

 Atlantic samples (Figure 21). Thus the Indian 

 Ocean population would appear to be the one 

 genetically and geographically intermediate in 



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