Fish Fauna of Johnston Is. — Gosline 
of this difference may be attributable to the 
any rate, it seems from the above data that 
(presumably) environmental differences with- 
in areas may play a considerable role in the 
differentiation of gill raker counts, and this 
must be kept in mind in assessing the bio- 
logical significance of the difference between 
samples. 
Even allowing for this variability within 
areas, the gill raker counts for K. sandvicensis 
at Midway seem to be considerably higher 
than for other areas. The increase in Midway 
counts over those of Pearl and Hermes reef 
some 90 miles away is especially curious. 
Among the samples of K. marginata about 
all that can be said is that the counts for the 
Johnston and Wake specimens seem to be 
particularly high. On the other hand the few 
counts from Penrhyn, about as far south of 
the equator as Johnston and Wake are north, 
are low. Any attempt to correlate gill-raker 
473 
counts with water temperatures in this spe- 
cies complex on the basis of the present 
material seems fatuous. 
Summing up the data for the Kuhlia sand- 
vicensis-marginata complex, it may be said 
that the Johnston and Wake samples show 
absolutely no indication of introgression 
from the Hawaiian species so far as gill-raker 
counts are concerned. Conversely, the sam- 
ples from the high Hawaiian islands show no 
sign of intermixing from K. marginata. How- 
ever, the low Hawaiian island samples, par- 
ticularly those from Midway, show a trend 
toward the southern form. Since Midway has 
the water temperatures and total environment 
least like those of the areas in which K. 
marginata lives, the similarity of the Midway 
K. sandvicensis to K. marginata can best be 
explained by introgression from the latter 
species. Whether such introgression is brought 
about through specimens of K. marginata 
coming in from Johnston, Wake, Marcus or 
elsewhere remains unknown. 
TABLE 6 
The Number of Pectinate Gill Rakers on the Lower Limb of the First Gill Arch in Samples of the 
Kuhlia sandvicensis-marginata Complex 
SPECIES and locality 
NUMBER OF 
SPECIMENS 
AVERAGE 
COUNT 
STANDARD 
DEVIATION 
AVERAGE 
STANDARD 
LENGTH 
IN MM. 
K. sandvicensis 
Hawaiian Islands 
Midway (July, 1949) 
25 
25.40 
1.24 
61.0 
Midway (June, 1950) 
29 
25.28 
0.80 
over 100* 
Pearl and Hermes 
22 
24.18 
0.73 
over 100* 
Lisianski 
39 
24.41 
0.75 
over 100* 
French Frigate 
5 
24.20 
61.8 
Kauai 
25 
24.64 
1.25 
135.6 
Oahu (Waimea,, 1948) 
37 
24.41 
0.75 
69.6 
Oahu (Waimea, 1949) 
33 
24.82 
0.73 
62.6 
Hawaii (Puna Coast) 
22 
24.77 
0.87 
47.0 
K. marginata 
Johnston 
9 
27.33 
0.50 
180.0 
Line Is.: Palmyra 
5 
26.40 
156.6 
Phoenix Is.: Canton 
3 
26.00 
198.3 
Cook Is.: Penrhyn 
6 
25.67 
71.8 
Wake 
18 
27.20 
1.24 
. 121.0 
Marcus 
5 
. 26.00 
84.8 
Large specimens discarded in field. 
