150 THE ROYAL SOCIETY OF CANADA 



collections from Vancouver Island, especially those of early spring; 

 but the distinctive features are so few that the identity of species is 

 not easily determined. In the most frequently occuring forms the 

 frustules in zonal view are simple regular prisms, without enlargement 

 either at the middle or ends and with rather inconspicuously striated 

 margins. Most of these appear to belong to Fr. capiicina Desm. 

 which is now placed in the new genus Staurosira, which includes the 

 species with strong and easily visible striation with an ample smooth 

 central area on the valval face. 



NITZSCHIA. 



Fifteen species of this genus have been identified from Vancouver 

 Island, and are listed on another page. Perhaps the most common, 

 at least in certain gatherings, is N. seriata CI. which may possibly be 

 the P seudonitzschia migrans Cleve of the general list reported by Dr. 

 MacKay. It is a characteristic plankton Diatom, common in north- 

 ern waters, and easily recognized by its long string of frustules over- 

 lapping at the ends. N. longissima^Nitzschiella Bréb. is less common 

 but more conspicuous owing to its great length and striking form. 

 It exhibits two varieties. 



RHIZOSOLENIA. 



The representatives of this genus are all remarkable for their 

 large size and cylindrical form, as well as for the prominence of their 

 terminal spines. Rh. setigera Brightw. and Rh. styliformis Brightw. 

 are the forms usually met with in the Vancouver waters as they are 

 in those of the Atlantic. In setigera the valves are cone-shaped, 

 pointed and only slightly inclined, while the processes, at first cylin- 

 drical and solid at the base, subsequently become abruptly drawn out 

 into hair-like bristles; but in the Vancouver forms the spear-head 

 enlargement figured by R. Ramsay Wright from Canso, Nova Scotia, 

 (Contr. Biol. St'ns Can.), has not been observed. Rh. styliformis 

 is a smaller species with valves obliquely pointed, and the process at 

 the end solid with two lateral ears. 



A single specimen of what was thought to be Rh. hebetata Bailey 

 was observed. Gran recognizes two varieties of this species — hie- 

 malis, long-spined, with thick and solid processes perforated at the 

 base and the cell wall thick; and semispina with long drawn out 

 valves and processes which are produced into hair-like bristles, the 

 cell wall being only of medium thickness. The former is the type 

 of Bailey's Rh. hebetata. 



