82 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 122 



on which to base a meaningful study of north-south trends. 



I have entered the fin ray averages of Pacific Ocean populations at 

 their geographic locations on a map in a search for more complex 

 trends. T could observe only that similar averages tended to group 

 in certain locations, but there was no obvious relationship of widely 

 separated areas with similar averages (e.g., the Line Islands and the 

 Marshall Islands) or with averages of populations along island groups 

 radiating out from them. 



Fin ray counts and averages of populations (table 34) from the 

 South China Sea (SCS) and Indian Ocean (10) indicate no trends, 

 nor are these averages similar to those of Pacific Ocean specimens 

 from similar latitudes : 



Strasburg (1955) reported that north-south differentiation in 

 number of soft dorsal and anal rays occurred in the western Pacific 

 salarine blenniid, Istiblennius edentulus (which has much the same 

 distribution in the Pacific Ocean as does E. striatus). The average 

 number of rays, he reported, tended to decrease from the northern 

 latitudes to the equator and then to increase from the equator south 

 as one progressed southeasterly along what Strasburg called the 

 "main band" of islands (Wake, Marianas, Marshalls, Gilberts, Samoa, 

 Tuamotus, Fijis, Societies, Gamblers). Strasburg gave no reasons 

 to support his choice of the main band of islands upon which he based 

 his evaluation. 



Strasburg calculated regression lines for fin ray counts for the main 

 band of islands based on average annual temperatures (which are 

 generally correlated with latitude, decreasing north and south from 

 the equator). He tlien set confidence limits at p .01 level and cal- 

 culated the expected range of fin ray averages based on average 

 annual temperatures for populations of /. edentulus from island groups 

 outside the main band and demonstrated that almost all the averages 

 fell within the range of those expected, inferring, thus, tliat there is 

 some relationship between temperature and average fin ray count. 

 Here it should be noted that if one were to eliminate the single high 

 dorsal ray average for the Gambler specimens from Strasburg's 

 calculations, his regression for dorsal fin rays would be hardly different 

 from a straight line. 



The temperatures Strasburg used were obtained by averaging the 

 surface temperatures for the months of F'ebruarv and August as 



