178 NUTTING 



account of the presence of perpetual ice in the form of glacier 

 fronts and bergs, the water must be very cold the year around. 

 Such a combination of conditions is particularly favorable to 

 Hydroid life and accounts for the remarkably rich collections 

 made at these places and also for the presence of so many arc- 

 tic species. In this connection it is interesting to note the fol- 

 lowing paragraph written about twenty five years ago by Dr. 

 Dall : " The material derived from the northwestern coasts of 

 America, from Cook's Inlet south and east, indicates a series of 

 Arctic colonies in favored localities, the future exploration of 

 which offers a labor of the highest interest. These colonies are 

 situated where the depth of water, the drippings of glaciers, and 

 the high and adjacent shores of the Great Archipelago combine 

 to reduce the temperature of the water below its apparently 

 normal isotherm. Cook's Inlet affords one of them, one exists 

 in the Gulf of Georgia, and others only await further explora- 

 tion." 1 It should be noted, however, that nearly all of the 

 Arctic species are well known forms belonging to the ' Holarctic 

 Province ' of authors, and that these species are of practically 

 continuous distribution on all coasts in northern regions so far 

 as explored. 



In the same paper, Dr. Dall divides the coasts of America 

 from Monterey, California, north and west, into three faunal 

 areas, as follows : (a) the Oregonian, extending from Monterey 

 to the Shumagin Islands ; () the Aleutian, extending from the 

 Shumagin Islands to the end of the Aleutian chain, and north- 

 ward to the winter line of floating ice in Bering Sea ; (c) the 

 Arctic, limited on the shore line to the winter line of floating 

 ice and passing southward indefinitely in deep water. 



This paper deals chiefly with what Dr. Dall would call the 

 Oregonian Fauna, only seven species having been secured to 

 the westward of the Shumagin Islands. Of these seven species 

 five are also found in his Oregonian Fauna, and the other two 

 are new and known, thus far, from only one locality. 



Dr. Clark, in reporting on the collection made by Dr. Dall, 

 enumerates 25 species that occur west and north of the Shu- 

 magin Islands. Of these 25 species we now know that sixteen 



Proc. Acad. Nat. Sciences, Philadelphia, p. 206, 1876. 



