ío 



10 



ON NEW FACTS LATELY PRESENTED IN OPPO 

 SITION TO THE HYPOTHESIS OF BIPOLARITY 



OF MARIM: FAUNAS. 



ARNOLD I, QK1 MANN. 



Bipolarity in the: distribution of marine animals, indicated 

 by The'] as early as 1SS6, has been proposed as a theory by 

 G. Pfeffer. 3 Later, J. Murray 2 accepted the theory and tried to 

 mpport it by a careful collection of facts. From the beginning 

 the present writer, chiefly relying on the irr, tion of the 



distribution of decapod crustaceans, vigorously objected to the 

 theory, and expressed his views as early as 1894 and 1895,* 

 contending that the cases introduced by Pfeffer were not cor- 

 rect, in [896, after the publication oi Murray's paper, the 

 writer published an article 4 dealing with the subject mere 

 closely, and arrived at the conclusion that bipolarity docs not 

 exist as a general law of distribution among the decapod 

 .crustaceans, and that it seems very improbable that such a 

 law may prevail arnon^ other groups of animals. 



J. Murray disregarded these objections, and on different 

 occasions^ continued advancing bipolarity as a distributional 

 fact, which called forth repeated objections on the part of the 

 writer.* Since then (i%()7) other zoologists have taken part in 



1 Versuch über die erdgeschichtliche Entwicklung der jetzigen Verbreitung:- 

 verhältnt e unserer ThUrwelt, p. 38. Hamburg, 1891. 



2 '/ran:. Roy ',<><. Edinburgh, vol. xx/viii (1896), No. 2, p. 494. 



: Jru/u://ic henkschr., Bd. viii (1S94), p. 7^, and (,rundzüge der marinen Thier- 



geographies p. 52. (Tbk latter hook was issued in December, 1895, ' /ut - bear« the 

 date 1896 on the title-page.) 



4 ZW. /////;-//, .Vys/., fid. « (1896), pp. 'J l Jf. 



■ Nature, vol. lv (1897), \o. 1430, p. 500, and in 7/^ Geograph. Júurn., vol. xii 

 (1898), No. 2. 



*' ZW. Jahrb., . ( >y>t., Bd. x (1S97), p. 2/7, and Science, vol. viii (1898;, p. $l6< 

 Pfeffer {Zool. Anzeig., VA. xx, September, '897) has rf-A^rr'A to the first of these 

 objections; but since he does not discuss the matter at all, and only douhts the 

 ability of the writer to investigate this topic, it is better not to consider this note. 



5*3 



