T' 



65 



ROYA ANGLICA G. S. West, A NEW BESMID ; 



WITH AN EMEI^DED DESCRIPTION OF THE GENUS ROYA. 



By William J. Hodgetts, M.Sc. 



This new species of Roya was found in early April 1916 in some 

 very shallow water in the swampy corner of a meadow at Quinton, 

 near iiirmingham. It occurred in practically a pure growth (the 

 only other Alg* present being a few Diatoms) which formed soft 

 gelatinous pale-green masses, floating on the surface of the water. 

 Countless numbers of vegetative cells, many of them in process of 

 conjugation, were present, while zygospores occurred in thousands. 

 The Alga as soon as found was submitted to the late Prof. G. S. West, 

 who pronounced it to be a new and very interesting species of Roya : 

 one, moreover, wliich made necessary some moditication of the 

 characters on which this genus is founded. Prof. West made 

 drawings of the Alga — which he named Roya anglica — and was to 

 have published an account of it in the " Algological Notes " which 

 he was contributing to this Journal ; but his untimely death pre- 

 vented this from being carried out. The drawings have been placed 

 in the hands of the present writer, and it seems desirable that a short 

 description of the species should be published. Unfortunately, the 

 Alga quickly disappeared from its original locality and has never 

 been observed since, except very occasionally as isolated cells in water 

 from the corner of the same meadow. 



The facts concerning this Alga have been taken from some notes 

 and drawings made in 1916 and from characters observed in some 

 permanent preparations, and from Prof. West's drawings. 



The fonn of the vegetative cell is cylindrical or subcylindrical, 

 unconstricted, and very slightly tapering towards the extremities, the 

 latter being subtruncate (A-D). The cells are sometimes quite 

 straight but generally somewhat asymmetric, a slight but never 

 regular curvature being present, especially in the longer cells, while 

 the greatest width of the cell is often not in the middle but nearer to 

 one end than the other (see A) ; in extreme cases the shape is almost 

 clavate. The size varies considerably, the length being 35-80 

 ( — 112) ^, the greatest width 7-5-9 \x ; the ends are 5-7 /^ wide. The 

 cell-wall is colourless and quite smooth, of moderate and uniform 

 thickness, except at the ends of the cell where it is somewhat thicker 

 than elsewhere (A-D). It is impossible to distinguish the line of 

 demarcation between old and new semi-cells, but the younger end 

 of the cell can often be determined by the fact that the thickening of 

 the extremity of the cell- wall at this end is frequently less pronounced 

 than it is at the older end. 



Neither in the unstained condition nor after staining with gentian- 

 violet could any signs of pores or of an}^ other structure be observed 

 in the cell-\vall, even under very high powders. Liitkemiiller * has 

 examined the cell-w^all in other species of Roya and always found it 



* " Zur Kenntnis der Desmidiaceen Bolimens," Verhandl. der k.-k. zool.-bot. 

 Ges. Wien, Ix. 479, 1910. 



Journal of Botant. — Vol. 58. [March, 1920.] f 



