DEPARTMENT OF MARINE BIOLOGY. 195 



Tutuila studies favor the belief that the broad platform fringing the island, 

 which has made it possible for the barrier reef to form, need not, in the main, 

 have been cut under the conditions of glacial control. 



The Fishes of Samoa, by W. H. Longley. 



Samoa so abounds in fishes that 7 weeks spent in the islands proved too 

 short a time to become thoroughly acquainted even with those species which 

 occur in Pago Pago Harbor. The following paragraphs, therefore, embody- 

 only the results of a preliminary investigation of the fishes of the group. 



Between the 5th of July and the 24th of August, 150 species were identified 

 and 47 additional were distinguished without positive identification. Some of 

 those identified, such as Pseudupeneus porphyreus and Batistes bursa, have not 

 been reported from the islands hitherto. Among the species recognized but 

 not to be identified by aids available at present a number will prove to be new 

 to Samoa, if not new to science. 



Not at every point, however, did investigation extend the list of Samoan 

 fishes. In two cases it appears that systematists have recognized as distinct 

 species what are only alternative color-phases of a single one. This is true of 

 Variola touti and V. flavimarginata, as well as Pomacentrus nigricans and P. 

 albofasciatus. In the case of either pair of forms the actual change from the 

 one to the other may be observed in the field, though (by reason of its abun- 

 dance) more readily in the case of Pomacentrus than Variola. 



Of 197 species that came under observation, 56 are able to change color, 

 shade, or pattern. Some, indeed, are changeable in all three respects. It is 

 to be anticipated that an increase both in the absolute and relative amount of 

 variabihty observed will follow more extended study. 



To determine under what conditions the varied color-phases of the change- 

 able fishes are displayed, and what relation both changeable and unchangeable 

 hues bear to those of the normal surroundings of the various species, is the 

 chief purpose of the investigation. To settle these points it is imperative to 

 secure detailed information regarding the distribution and behavior of each 

 species. This information must be gathered piecemeal, as opportunity ofifers. 

 Until the investigation is far advanced it is therefore of a heterogeneous char- 

 acter and not readily summarized; but in general it may be said that the more 

 narrowly a fish is confined to a certain environment, or the more commonly it 

 occurs in such, the more clearly its color tends to reproduce those dominant 

 in its surroundings. 



This appHes to single species, such as Abudefduf dicki, which is found in the 

 neighborhood of Acropora, more particularly perhaps about A. leptocyathus, 

 whose brown color it repeats. It also applies very clearly to such groups as 

 Pseudupeneus multifasdatus, Halichoeres trimaculatus, Scolopsis trilineata, 

 Balistapus aculeatus, and Monotaxis grandoculis, which may be seen together 

 over clear sand, to the shade of which they are without exception capable of 

 adapting themselves. It also applies most strikingly to a number of species 

 which to a greater or less degree are capable of putting off their bottom-colors 

 when they rise toward the surface in deep water. No fish may more justly 

 exempUfy this class than the great surgeon-fish Hepatus matoides, which, when 

 near bottom, may be black except for its tail and particolored yellow pectoral 

 fin, but which 25 feet higher in the water, away from the reef-face, appears in 

 pure pale blue-gray of lowest visibiHty. 



In conclusion, the work of the past season shows that Samoa possesses a 

 very large and diversified fish fauna, and that Pago Pago Harbor is so large, 

 possesses such a degree of protection from the ocean, and has a shore-line of 



