A HISTORY OF SURREY this county in a paper by the writers which appeared in the Journal of the Royal Microscopical Society for 1897.' Hormiscia subtilis, De Toni, var. tenerrima, Kirchn. Esher Common, Richmond Park and Wimbledon Common subtilis, De Toni, var. variabilis, Kirchn. DevirsJumps(Frensham),Esher and Esher West-end Commons Microthamnion Ktitzingianum, Nag. Esher Common, Richmond Park and Puttenham Common Gonatonema Boodlei, West and G. S. West. A species new to science of a very in- teresting and rare genus ; Mitcham Common Spirogyra Spreeiana, Rabenh. Esher West-end Common decimina, Kfitz. A distinct new variety ; Frensham Little Pond Penium subtile, West and G. S. West. A species new to science ; abundant on Thursley Common Closterium siliqua, West and G. S. West. New to science ; Esher West-end Com- mon Cosmarium Subcucumis, Schmidle. Esher West-end and Wimbledon Commons ocellatum, B. Eichler and Gutw., var. in- crassatum, West and G. S. West. A new variety ; Thursley Common bioculatum, Breb., var. hians, West and G. S. West. A new variety ; Putten- ham and Thursley Commons aspherosporum, Nordst., var. strigosum, Nordst. Puttenham Common geometricum, West and G. S. West. Puttenham Common helcangulare, Nordst. Thursley Common Heimerlii, West and G. S. West. Thursley Common and Mill Pond east of Chapel Wood sphagnicolum, West and G. S. West. A species new to science ; Thursley Common difficile, Lutkem. Thursley Common Sinostegos, Schaarschm., var. obtusius, Gutw. Puttenham Common Portianum, Arch., var. orthostichum, Schmidle. Puttenham Common Nathorstii, Boldt. Mill Pond east of Chapel Wood subbroomei, Schmidle. Mill Pond east of Chapel Wood Cosmarium Ungerianum, De Bary, var. sub- triplicatum, West and G. S. West. A new and very distinct variety of a very rare species not previously known from the British Isles ; Mill Pond east of Chapel Wood ellipsoideum, Elfv., also its var. minus, Racib. Both on Thursley Common subarctoum, Racib. Esher West-end Common gonioides, West and G. S. West. Thurs- ley Common Staurastrum trachytithophorum, West and G. S. West. A species new to science ; Thursley Common tunguscanum, Boldt. Puttenham Common nodosum, West and G. S. West. A species new to science; Thursley Com- mon Staurastrum rostellum, Roy et Bisset, var. erostel- lum, West and G. S. West. A new and very distinct variety ; Thursley Common tetracerum, Ralfs, var. validum, West and G. S. West. A new variety; in Mill Pond east of Chapel Wood Heimerlianum, Lutkem., var. spinulosum, Lutkem. Thursley Common margaritaceum, Meneg., var. subcontortum, West and G. S. West. A new variety ; DeviFs Jumps (Frensham) Arthrodesmus Incus, Hass., var. subquadratus, West and G. S. West. A new varietyi; Chobham Common Sphaerozosma vertebratum, Ralfs, var. latius, West and G. S. West. A new variety ; Esher West-end Common Hyalotheca neglecta, Racib. A rare species ; very abundant on Thursley Common Chlamydomonas Kleinii, Schmidle. Barnes, Chobham, Esher and Wimbledon Commons Dactylococcus dispar, West and G. S. West. A species new to science ; occurring on old wood at Dorking Scenedesmus granulatus, West and G. S. West. A species new to science ; Richmond Park Rhaphidium polymorphum, Fresen., var. mirabile. A very remarkable new variety ; Wimbledon Common polymorphum, Fresen., var. tumidum. A new variety ; Puttenham Common 1 As the British Desmids and British Freshwater Algte by Mr. C. Cooke only contain a part of the species now known for Britain, the writers have also used standard works such as Bornet and Flahault's Revision des Nostocac^es Hetencystites, Gomont's Monographic des Osc'tHar'tites, as well as standard Swedish, German, Italian and Polish works ; also published works of the writers themselves, as well as using the original figures contained in such standard works as Ralfs British Desmidiea. 58