262 



BULLETIN OF THE BUREAU OF FISHERIES. 



CHARACTER AND RELATIONSHIPS OF THE HAWAIIAN FAUNA. 



From the foregoing it will be seen that so far as is known the Hawaiian fauna includes 

 about 25 named species of cephalopods, together with half as many more uncertain forms, 

 some of which are doubtless worthy of recognition but which are only familiar to us by 

 specimens either too young or too poorly preserved for a positive determination of the 

 species. The total number of genera represented is 24, or about two-thirds as great as 

 the total number of species. This is due to the fact that the genus Polypus with 9 forms 

 listed (at least 5 of them doubtful), Argonautawith 2 species, and Abralia with 2 species, 

 are the only genera which appear more than once in the list. (Owing to various facts 

 which are to be summarized on another page, Rhyncoteuthion should obviously be excluded 

 from the present discussion.) The apportionment of the fauna among higher groups 

 is conveniently shown in the following table : 



Table I. 



genera rep- 

 resented. 



Named 

 species. 



Unnamed 

 or doubt- 

 ful species. 



Octopoda . 



Myopsida. . 

 Oegopsida . 



Total. 



One very striking feature which is brought out with particular emphasis in such a 

 table is the surprising weakness of the myopsid element in the fauna. Of the four myop- 

 sid genera, one is Sepioteuthis, the remaining three are Sepiolidae, and even of each of 

 these but a single species has come to hand." The total absence of any representatives 

 whatsoever of the great genera Loligo and Sepia in any of the collections was entirely 

 unexpected. Of course Hawaiian species of one or both of these groups not improbably 

 may yet come to light, but in any case I feel that the series of specimens collected by the 

 Albatross is so representative that we may assert with confidence that neither genus 

 attains any very great development in these waters, or even the prominence which we 

 might reasonably expect when we consider what a dominant element they compose 

 in the fauna of the Malaysian Archipelago as well as of Japan. Loligo especially is so 

 abundant a genus and so cosmopolitan that it would be hazardous with our present 

 knowledge to deny its occurrence anywhere. In the case of Sepia, however, it should 

 be remembered that with the exception of a solitary and ill-authenticated record from 

 the West Indies, not a single species is known from the waters adjacent to the American 

 Continent nor indeed from the entire Western Hemisphere. The group being mainly a 

 littoral one, we thus have a priori grounds for suggesting that wide oceanic areas may in 

 some way form a special barrier to its dispersion. If this be true we should perhaps 

 expect other littoral forms, such as the Polypi, to be distributed in accordance with the 

 same principle ; but this, as we shall see later, does not appear to be the case. An explana- 

 tion of this anomaly may be found in the hypothesis that the dissemination of these 

 other forms took place at a more ancient period. That the rise and dissemination of 



a It should be remembered, however, that to one of these species. XLuprymna scolopes. belongs the distinction of being by far the 

 most abundant Hawaiian cephalopod. Nearly one-third of the total number of specimens examined are referable here. 



