28l 



THE DIATOM-FLORA OF MARTIN BECK, YORKS. 



M. H. STIL.ES, F.R.M.S. 



For some time the Doncaster Scientific Society has been 

 engaged in investigating the Natural History of Martin Beck, 

 a district lying about midway between Bawtry and Tickhill, 

 and about nine miles by road from Doncaster. Our first 

 visit was paid in 1910, and I then made gatherings of diatom- 

 aceous material, and, from time to time, as leisure permitted, 

 worked upon them. 



The results were extremely interesting, but in anticipation 

 of a more thorough examination, the publication of the details 

 was suspended. Last year, hoM^ever, the investigation was 



resumed, and very useful work was done by several of our mem" 

 bers and friends. On my part, the old slides were more 

 thoroughly gone over, additional gatherings were made and 

 examined, and I now have the pleasure of submitting a fairly 

 complete record of the Diatom-Flora of a district which has 

 yielded so far 106 species and varieties, 23 of which are not 

 included in West's Alga-Flora of Yorkshire, and 40 have not 

 been previously recorded for the South-west division of the West 

 Riding. 



798 Amphora ovalis Kutz. 

 A. ovalis var. affinis. 



802 Cymbella ciispidata Kutz. 



803 C. siibaeqiialis Grun. 

 805 C. affinis Kutz. 



*C. aequalis Wm. Sm. 



*C. pusilla Grun. 

 8n fC. Helvetica Kutz. 

 812 \C.laevis Naegeli. [Ehr. 



820 Stauroneis Fhoenicenteron 



*Stauroneis Gregorii Raits. 

 821 S. gracilis Ehr. 

 824 S. anceps Ehr. 



t5. anceps var. linearis. 



826 Navicula nobilis Ehr. 



t N. nobilis var. dactylus. 



827 A'^. major Kutz. 



828 N . viridis Kutz. 



N. viridis var. commutata. 

 * N. Danensis. 



1918 Sept. I. 



