DISTRIBUTIONAL PROVINCES OF MARINE BRYOZOA 

 IN THE INDO-PACIFIC REGION ^.^ 



By Yaichiro Okada ^ 



and 



Shizuo Maw atari * 



Although the present condition of our knowledge on the bryozoan 

 fauna of the Indo-Pacific Region is not yet quite satisfactory, the accu- 

 mulated works of numerous authors have revealed much of the truth 

 on the distribution of the group. The following authors contributed 

 much in the faunal study of each region: Waters (1909, 1910, 1913) 

 and Thornely (1905, 1907, 1912, 1916) on the Bryozoa of the Indian 

 Ocean; MacGillivray (1880-1891), Kirkpatrick (1888, 1890, 1924-1929), 

 Waters (1887, 1889) and Hastings (1932) on that of Austraha; Harmer 

 (1915, 1926, 1934) on the Siboga collection from the East Indies; Canu 

 and Bassler (1929) on the Albatross collection in the ¥h iippine region; 

 Ortmann (1889), Okada (1917, 1918, 1921, 1923, 1929) :.nd Silen (1941, 

 1943) on Japanese Bi70zoa; Canu and Bassler (1927) on the Hawaiian 

 forms; Smitt (1872), Robertson (1900, 1905, 1908, 1910), O'Donoghue 

 (1923, 1925, 1926), Hastings (1930) and Osburn (1950, 1952) on the 

 Bryozoa of the Pacific coast of America. 



In the course of our systematic study on the Cheilostomatous Bryo- 

 zoa, on one hand, a large number of species were newly found distri- 

 buting in the Japanese waters, and we were rather surprised to find 

 how numerous were the species common to the Malayan region. The 

 present paper is the preliminary report on the distribution of the Indo- 

 Pacific Bryozoa. 



Geographical Isolation 



According to the recent progress of studies on the evolution, the 

 differentiation of species is said to be accelerated by the geographical 

 isolation in geological age. The proposition of the distributional prov- 

 inces are, therefore, to be based at first on the palaeogeography of the 

 Indo-Pacific Region. The Cheilostomata, that composing the largest 

 part of the recent marine Bryozoa, appeared in the Jurassic, and ex- 

 panded into so many species in the Upper Cretaceous time. As the 



^ Contributions from the Fisheries Division, Mie Prefectural University. No. 213. 



^ Contributions from the Research Institute for Natural Resources. No. 623. 



■" Dean, Faculty of Fisheries, Mie Prefectural University, Tsu, Japan. 



* Of the research staff of the Research Institute for Natural Resources, Tokyo, Japan. 



391 



