78 



REFERENCES TO PLATE :— L— Staurocarpus gracillimus Hass. in 

 conjugation x 400. 2.— ^^dogonium Landsbroughii Hass. showing spores 



X 200. 3. — Spirogyra Weberi Kutz. x 100 ; a, filaments ^ empty, 5 with 

 spores therein ; h, conjugating filaments, impregnation. 4. — Scytonema 

 myochroum Agdh. x 100, showing filaments in gelatinous sheath. 5. — An 

 Alga parasitic on another Alga ; Closterium Lunula Midler attacked by 

 Olpidium endogenum Braun x 200. 6. — Tetrapedia Crux-MichEeli Rtinsch 



X 580. 7. — Aphanizomenon flos-aquae Ralf.-i x 400. 8.— Micrasterias fim- 

 briata i?a//s x 200. 9. — Arthrodesmus incus ^ass. x 500. 10.— Euastrum 

 elegans Brih. x 500; state of vegetative cell-division. 11. — Euastrum 

 gemmatum Breh. x 650. 12. — Cosmarium Meneghinii Brih. x 500. 13. — 

 Xanthidium cristatum Breh. x 500. 14. — Staurastrum punctulatum Breh. ; 

 empty semi-cells of two copulating fronds, with zygospore x 500. 15. — 

 Tetmemorus leevis Kutz. x 400. 16. — Closterium Eboracense Turner MSS, 



X 500. 17. — Closterium speciosum Turner MSS. part of frond x 500. 

 [Fig. 5 is after Archer, in Q. J. Mic. Sci. ; the rest are after nature, and, 

 except 17, are from Yorkshire specimens. — W. B. T.] 



