298 
PACIFIC SCIENCE, Vol. IX, July, 1955 
120* 140“ 160“ E 180“ 160° W 140“ 
Fig. 1 . Map showing relationships between various island groups of the Pacific Ocean. Circles denote areas 
from which specimens were examined. 
the relatively distant relationship between the 
fishes of the Marshalls and Hawaii, as com- 
pared to the closer one between those of the 
Marshalls and the East Indies. 
In order to investigate the second hypo- 
thesis the study was restricted to a single 
blenny, Istiblennius edentulus. This species is 
widely distributed throughout the Indo- 
Pacific region, but has evolved slightly differ- 
ent forms in certain isolated geographical 
areas. It, together with its dose relatives, is 
a tidepool inhabitant and quite demersal in 
its habits. Spawning occurs in tidepools but 
the postlarvae are pelagic and are undoubtedly 
the stage in which dispersal of the species has 
occurred. Specimens from numerous island 
groups have been examined, and meristic data 
have been compared to an environmental con- 
dition, water temperature, in this work. 
The writer wishes to thank Dr. Leonard P. 
Schultz of the U. S. National Museum, for 
making available the Museum’s large store of 
Indo-Pacific blennies. Thanks are also due to 
Dr. William A. Gosline and Mr. John E. 
Randall, both of the University of Hawaii, 
for the loan of their collections of Wake 
Island and Gilbert Island blennies, re- 
spectively. 
GEOGRAPHIC AND PHYSICAL CONSIDERATIONS 
The Central Pacific Ocean, using the term 
rather loosely, is crossed by a band of islands 
running in a general southeasterly direction 
from the Marianas to the Gambiers (Fig. 1). 
This strip is about 5,500 miles in length and 
covers approximately 50 degrees (3,000 miles) 
of latitude. Its component islands are quite 
regularly spaced across the Pacific, and thus 
form a convenient array for a study of the 
effects of latitude, and hence temperature, on 
fishes. Because of the possibility of fish move- 
ment between islands in this band, with re- 
sultant interbreeding and masking of tem- 
perature effects, it was deemed advisable to 
study specimens from various remote geo- 
graphical areas. The following list summarizes 
collection locales for specimens examined; 
those regions marked with an asterisk do not 
lie on or particularly near the main band of 
islands. 
*Western Hawaii (Necker, Laysan) 
*Eastern Hawaii (Oahu, Maui, Hawaii) 
Wake 
Marianas (Guam, Saipan) 
*Philippines (Mindoro, Balabac) 
