Fakquhar. — Bi/folariti/ of Littoral Mariiie Bmmas. 131 



Art. X. — Note on the Bipolarity of Littoral Marine Faunas. 



By H. Farquhar. 

 Communicated by A. Hamilton, Director, Colonial Museum. 



[Bead before the ]Velli7}gton Philosophkcd Society. \st August, 1906.] 



The littoral marine fauna of New Zealand, in common with the 

 land fauna, consists of several distinct elements. In all or 

 nearly all the groups which have been worked up we find two 

 comparatively small elements, which are nevertheless more 

 interesting than the other parts of our fauna — namely (1) an 

 autochthonic element, consisting of species which are peculiarly 

 Neozelandian in type, and. having no relations in any other 

 parts of the world, are entirely distinct from all other forms ; 

 these have arisen in the New Zealand area in extremely remote 

 geological times ; and (2) a representative element, consisting 

 of species which are identical or closely allied to species inhabiting 

 the northern temperate or Arctic regions. The latter are known 

 as bipolar forms. The autochthonic element is stronger in the 

 land fauna, but it is also well marked among our marine ani- 

 mals ; and. although only a faint trace of the northern element 

 is found among our terrestrial animals, it is much more strongly 

 marked in the marine fauna. 



The bipolar forms are thought by some naturalists to be the 

 remnant of a fauna which was cosmopolitan in very early times, 

 Avhen a more equable climate probably obtained all over the 

 world. 



Of Hydroida we have six littoral species in New Zealand 

 identical wnth European forms : Ohelia geniculata, Sertularia 

 operculata, Sertularella polyzonias, Plumularia setacea, Antennu- 

 laria antennina, and Tubidava fruticosa. Campanularia calicu- 

 lata var. makrogona, which occurs freely in Wellington harbour, 

 is a distinct species, for it always has the large type of gonangia 

 figured by Bale in the Proc. Linn. Soc. of New South Wales, 

 1888. It is closely related to the European species C. caliculata, 

 which occurs in Australia. Aglaophenia filicula occurs here 

 and at the Azores ; and almost all the genera are European. 



The sea-anemone Actinia tenebrosa, which is only found 

 between tide-marks, is the southern representative of, and 

 closely allied to, A. equina. The genera are almost all common 

 to both regions. Two New Zealand species known to me are 

 entirely distinct from all others — namely, Halcampactis mirabilisy 



