256 ANNALS OF SCOTTISH NATURAL HISTORY 



2/3. C. Lundellii, Delp. 



Var. ellipticum. West. Very rare. 



2/4. C. Scoticuin, West. Very rare. Perth Craig-an-Lochan 

 Glas Mhoel, (?) Ben Laoigh (Mr. W. West). 



(165.) C. tetragonum (Nag.), Archer. 



Var. pumilum, West. Very rare. Perth (or Argyle) Ben 

 Laoigh (Mr. W. West). 



(167.) C. Thwaitesii, Ralfs. 



Var. Scoticum, West. Rare. Kirkcudbright New Galloway 

 (Mr. W. West). 



POSTSCRIPT. 



Dr. Roy having unfortunately died when about half of this 

 work had appeared in print, leaving his notes for the rest in an un- 

 finished state, more especially as regards descriptions of new species 

 and varieties, it fell to me, as having been long closely associated 

 with him in the study of the Desinidiea;, and having in my possession 

 authentic specimens of most of the new forms, to endeavour to 

 supply what was wanting, and to revise the MS. very carefully tran- 

 scribed by his daughter, Miss Mary Roy. 



To bring the record up to date, there have been included, with 

 the author's consent, some new species and varieties published since 

 Dr. Roy's death by Mr. William West. 



It was Dr. Roy's special desire that my name should be 

 associated with his in all the new species now published, except 

 where otherwise indicated ; because, as he put it, we had worked 

 so much together that it would have been difficult to have made a 

 fair division, but by far the greater part of the work is the fruit of 

 Dr. Roy's patient investigation. 



J. P. BISSET. 

 Sept. 1894. 



ERRATA. 



Under STAURASTRUM, 36, for S. cornigentin read S. connttnm, Archer. 

 ,, COSMARIUM, 31. C. corlntla, for Plate III. read Plate II. 



,, ,, 57. C.jlariiin, after "frond smooth" read " and yellow 



in colour." 



DESCRIPTION OF SCOTTISH DESMIDIE/E, PLATE IV. Fig. i. Docidiitm 

 Farquharsonii, Roy, x 200. Fig. 2. Micrasterins angitlosa, Hantz., zygospore, 

 x 200. Fig. 3. Stanrastriini Farquharsonii, Roy : , front ; b, end ; x 400. Fig. 

 4. St. dilatdtum, Ehr. , zygospore, x 400. Fig. 5. XanthiJiiim qttadricorn utiiui, 

 R. and B : a, front ; />, end ; x 400. Fig. 6. Closterium Balmacarense, Turner, x 

 400. Fig. 7. C. Balmacarense, ft minor, Turner, x 400. Fig. 8. C. Scoticttin, 

 Turner, x 400. Fig. 9. C. Scoticum, var. Jus iforu>, Turner, x 400. (Figs. 5-9 after 

 Mr. W. B. Turner.) 



