ARCTIC-ALASKAN BRYOZOA 31 



be true. The patent facts remain that many of the species have consider- 

 able temperature tolerance, that there is no sharp line of demarcation 

 between the Bryozoa of the arctic and boreal zones, and that most of 

 those found in the Arctic Ocean are circumpolar in distribution, regard- 

 less of how they arrived there. 



The Bryozoa of the Atlantic-Arctic region — Greenland to the Kara 

 Sea — are probably as well known as those of any other part of the world. 

 The southward extension of the range of these has been traced along 

 the coasts of Labrador, Newfoundland, the Gulf of St. Lawrence and 

 southward to Cape Cod or farther. The Pacific-Arctic fauna is at last 

 well enough known to enable us to make safe comparisons. The southern 

 range of many of these species was determined by the earlier work of 

 Hincks, the O'Donoghues, and Robertson from southern Alaska and 

 British Columbia to along the coast of California. The very numerous 

 collections made more recently by Captain Allan Hancock in the Velero 

 III have further extended the southern range of numerous species in 

 the cooler waters off the coasts of Oregon and California. 



Bryozoa appear to thrive as well in the icy waters of the polar seas 

 as they do elsewhere, and the number of species is about the same — 

 compare the 192 species recorded from Greenland waters with the 203 

 listed from the West Indies and Gulf of Mexico. As for the 113 species 

 recorded from Point Barrow, Alaska, it must be remembered that this 

 collection was made in a very limited area and with simple dredging 

 apparatus, and that more extensive collecting will undoubtedly increase 

 the number considerably. 



Species of local distribution appear to occur frequently throughout 

 the Arctic Ocean, as they do elsewhere. Thus 11 of the species from 

 Point Barrow have not yet been noted elsewhere and have been described 

 as new. Similarly, a number of those formerly described from Green- 

 land, Spitzbergen, Franz Josef Land, etc., are as yet known only from 

 the type locality. No doubt some of these will be found to have a wider 

 range when our know^ledge of polar Bryozoa is more complete. It is 

 worthy of note that two species originally described from Spitzbergen 

 and not noted since, Hippodtplosia cancellata (Smitt) 1867 and Euritina 

 arctica Osburn {Discopora tmpressa Smitt, 1871, non Reuss 1846), ap- 

 peared in the Point Barrow collection, half way around the pole from 

 the type locality. 



The follow^ing table shows the distribution of the 113 species from 

 the Pacific-Arctic at Point Barrow, their occurrence in the Greenland 

 region and farther east, and also the southern range of the same species 



