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PACIFIC SCIENCE, Vol. IX, October, 1955 
remain uncollected elsewhere. In a few other 
fishes the Johnston specimens seem somewhat 
aberrant but probably do not deserve recog- 
nition as separate species. The principal sig- 
nificance of this low degree of endemism at 
Johnston lies in the demonstration that for 
Pacific island fishes 450 miles of open water 
without strong current systems has not re- 
sulted in much differentiation. 
The problem of evaluating Johnston as a 
filter bridge is far more complex. The present 
attack on it is divided into two facets. The 
first approaches the problem in terms of the 
relative strengths of the various components 
of the Johnston shallow-water fish fauna. The 
objective here is to obtain a general picture 
of the relationships of the fish fauna of John- 
ston Island. The second deals in greater detail 
with certain Johnston fishes that are repre- 
sented by different geographic forms south 
of the island than occur to the north. Its 
objective is to trace, in so far as possible, 
individual migration routes. 
Components of the Johnston Fish Fauna 
For purposes of the faunal analysis that 
follows, certain families of fishes have been 
excluded for one reason or another. First, 
those fishes that are pelagic or semipelagic as 
adults are omitted. For these, Johnston may 
have no significance whatever as a way point, 
and to include them would only obscure the 
data. Groups excluded from consideration for 
this reason are the sharks and rays, the needle 
fishes, half-beaks, flying fishes, carangids, 
barracudas, tunas, remoras, and all fishes 
taken from over 100 feet of water. Second, 
the parrot fishes and scorpaenids have also 
been excluded, but for the reason that at the 
present time they are so confused taxonom- 
ically as to make species records worthless 
zoogeographically. Finally, the species re- 
corded from Johnston by Halstead and Bunk- 
er (1954) only will not be considered as I 
have not been able to check their records. 
Fowler and Ball’s (1925) species have, on the 
other hand, been included because, as already 
mentioned, material upon which their more 
questionable identifications were based have 
been reexamined. Following is the reduced 
list of Johnston species, upon which the fol- 
lowing analysis is based. 
SPECIES CONSIDERED IN THE ANALYSIS OF THE 
JOHNSTON FISH FAUNA 
Central Pacific Species Reaching Johnston but 
Not Hawaii (Group B of Fig. 4) 
Leptenchelys labialis 
Muraenichthys gymnotus 
Muraenichthys schultzei 
Brachysomophis sauropsis 
Myrichthys bleekeri 
Echidna leucotaenia 
Uropterygius polyspilus 
Kuhlia marginata 
Parupeneus barberinus 
Abudefduf phoenixensis 
Epibulus insidiator 
Thalassoma quinquevittata 
Pervagor melanocephalus 
Ostracion solorensis 
Species Endemic to Johnston (Group G of Fig. 4) 
Centropyge flarnmeus 
Centropyge nigriocellus 
Hawaiian Species Reaching South to Johnston but 
Not Beyond (Group E of Fig. 4) 
Muraenichthys cookei 
Gymnothorax eurostus 
Uropterygius dent at us 
Apogon menesemus 
Apogon waikiki 
Parupeneus multifasciatus 
Cirrhitus alternatus 
Chromis leucurus 
Chromis vanderbilti 
Dascyllus albisella 
Halichoeres ornatissimus 
Thalassoma ballieui 
Thalassoma duperrey 
Chaetodon multicinctus 
Acanthurus sandvicensis 
Zonogobius farcimen 
Johnston Species Found Both in Hawaii and in the 
Central Pacific (Group C of Fig. 4) 
Saurida gracilis 
Synodus binotatus 
Conger noordziekii 
Leiuranus semicinctus 
Myrichthys maculosus 
Schultzidia johnstonensis 
Morin gua macro chir 
Anarchias allardicei 
Anar chi as cantonensis 
Anarchias leucurus 
Echidna polyzona 
Echidna zebra 
