92 • AMERICAN MIDLAND NATURALIST 



particular form. In the 1906 Postelsia there is a report by Isabel 

 Henkel (3) on the tide-pools near I ort Renfrew, B. C. from the 

 standpoint of their origin. It is mostly geological in character 

 and only incidentally refers to the algae there found. In that place 

 the tide-pools are of unusual character, large and deep, mostly 

 in sand-stone. In my study the term tide-pool includes anything 

 from a few pints to many gallons, left by the receding tide or 

 splashed by the spray above tide-mark. 



The plants were identified by comparison with the collection 

 at the Station and are named according to Setchell and Gardiner's 

 "Algae of North-western America," except Nos. i and 2, which 

 were identified and named by comparison with the private collec- 

 tion of A. S. Foster of Aberdeen, Wash, and with the collection 

 at the University of 111. in which these were named by Professor 

 Tilden of the University of Minnesota. No. 3, also, is the name 

 given by Professor Tilden to a specim.en from the north end of 

 San Juan Island, closely resembling, if not identical with those 

 classed by me under that name. There was some doubt as to 

 whether all the Prionitis should be classed as variations of one 

 species or as distinct species. Setchell, (5) discusses the same 

 question in regard to Ulva, holding that it is merely one species, 

 with much variation due to differences of environment. 



The list of places named does not pretend to cover the entire 

 Sound region but it is fairly typical and sufficiently exhaustive. 

 There are no pools at the south end of the Sound, where the shores 

 are mostly of clay or gravel. They are best represented about 

 the island regions and are most typical where these studies were 

 made. In an Ecological study by Wylie (9) of a small rocky 

 island off the south end of Lopez Island P. Lyallii is reported 

 further south than any point studied by me. Many regions were 

 studied or noted that are not included in this report. Only those 

 were included which were considered most typical. They were 

 mostly made at extreme low tide in order to make comparisons 

 possible. They are numbered in the order in which they were 

 studied. 



I. Brown's Island, chiefly west side and south end. 



1. Melohesia mar ginata, iormmg reddish-brown incrustations 

 on rocks at the high-tide line and in shallow pools. 



2. Peyssonnellia dubia, rather thick incrustations in crevices 



