NO. 1 OSBURN : EASTERN PACIFIC BRYOZOA CHEILOSTOMATA 3 



ma Canal collected by Dr. C. Crossland on the cruise of the S. Y. St. 

 George," listed 62 species, 27 from the Gulf of Panama, 33 from Gor- 

 gona, Colombia, and 37 from the Galapagos Islands. 



It appears that the only region of the Pacific coast that has been at all 

 adequately covered is the area from Puget Sound to southern Alaska. 

 Robertson apparently had very little dredged material at her disposal and 

 the number of species along the coast of the United States recorded by 

 her is limited almost entirely to shallovi^ w^ater forms. Of the several 

 thousand miles of coast from southern California southward we have had 

 no information except for the small areas covered by the papers of Hast- 

 ings and Canu and Bassler. Similarly we have had only very limited 

 knowledge of the bryozoan fauna from southern Alaska northward. 



The very extensive material dealt with in the present report should 

 give a fair picture of the occurrence of the coastwise Bryozoa of the 

 Eastern Pacific area from northern Alaska to Peru. No doubt many 

 species will be added in the future and certainly our knowledge of the 

 distribution will be greatly increased. 



Distribution 

 As might be expected, no sharp distributional barriers have been 

 found ; instead there are several areas which are more or less distinct in 

 their faunas but which intergrade with the regions to the north and 

 south. Still, when one considers a sufficient number of species from any 

 one of the following regions, the bryozoan facies is distinct enough ex- 

 cept where the boundaries overlap. There are some species which appear 

 to disregard temperature and range from the arctic to the tropics. 



1. The arctic area of the Pacific coast extends from Point Barrow, 

 Alaska (71° 18' N Lat.), the most northwesterly part of the North 

 American coast, southward to the Alaska Peninsula and the Aleutian 

 Islands. In the Bering Sea only a few scattering collections have been 

 made, but all of the species are high northern or arctic forms. Our knowl- 

 edge of this area has been recently much extended by the work of Profes- 

 sor and Mrs. G. E. MacGinitie of the Arctic Research Laboratory at 

 Point Barrow. In the summer of 1948 they collected more than 80 

 bryozoan species, practically all of which are known to occur elsewhere 

 in the North Polar seas. Several of these species extend their range 

 southward to British Columbia and even to northern California. 



2. A cool water region extends from the Alaska Peninsula southward 

 to Point Conception, California (about 35° N Lat.). The northern 

 part of this range is rather distinct from the southern portion, but so 



