[bailey-mackay] diatoms FROM VANCOUVER ISLAND, B. C. 145 



and Ditylum, but the cylinder is terminated at each end by a dome- 

 shaped cap, around the base of which is a circlet of long and straight 

 bristles, extending sometimes in the general direction of the cylinder, 

 more often widely divergent or stellate and sometimes reflexed parallel 

 to and closely adjacent to the cylinder itself. When seen in end-view 

 the frustule presents the form of a circular disc, ornamented with 

 conspicuous dots or circles near the edge, and surrounded by from ten 

 to fifteen or more bristles, radiating outwards and suggesting comparison 

 with Bacteriastnim. The bristles are, however, undivided. 



A more singular series of appendages is often found in the form of 

 somewhat lengthened finger-like processes. Their resemblance to the 

 pedicellaria of Echinoderms is very marked but their function is not at 

 all evident. I have seen no reference to these curious organs in any 

 literature at my command ; but they are common on the specimens of 

 this species observed in the waters of British Columbia. When both 

 sets of bristles are turned in the same direction the forms of Corethron 

 suggest comparison with a meteor or sky-rocket. Sometimes, but 

 more rarely, they are turned back and lie along and parallel to the 

 cylinder itself. Specimens presenting similar characters occur abun- 

 dantly in Antarctic waters, as shown in collections made by Amund- 

 sen's Antarctic Expedition and sent to me (Dr. Bailey) by Dr. Gran 

 of Christiania. 



BIDDULPHIA. 



The most common of the Biddulphias found in the Vancouver 

 collections is B. aurita (Lyng.) Bréb., a species of very wide distribu- 

 tion. It occurs in large numbers and exhibits much variety, being 

 found in both broad and narrow forms and in every stage of develop- 

 ment, some specimens being three or four times the size of others. 

 Some indeed depart so widely from the ordinary type as almost to 

 deserve recognition as distinct species. 



B. Roperiana Grev., B. ohtusa Ralfs., B. granulata Roper, and 

 B. siiborbicularis Grun, appear to be found in the order named, with 

 another form so distinctive as not to coincide with any other species 

 described in our literature. B. turgida Ehr. and B. polymorpha 

 (Ktz.) V.H. and another variety, with B. laevis Ehr. will be found 

 listed under the genus Cerataulus Ehr. B. antidihwiana will be found 

 under the genus Amphitetras Ehr. in the list with a rare related form. 



Besides the above there is present a species of large size which, 

 instead of having only the single prominence in the centre of each cell 

 as in B. aurita, has an additional prominence on either side of the 

 central one in addition to those of the angles which latter are without 

 processes or horns. In the undulating character of each valve sur- 



