A HISTORY OF HERTFORDSHIRE as occurring in Britain, 175 have up to the present time been recorded as growing within the boundaries of the shire. As might be expected, woodland forms, species of arboreal habit, and those which frequent rocks of a calcareous nature, are fairly numerous. The urban districts of the county are rapidly extending, and localities which formerly pos- sessed an interesting flora and were the habitats of several rare species, both of mosses and flowering plants, have recently been converted into building-sites. It is therefore to be hoped that in the near future in- creased attention may be paid to this branch of Hertfordshire botany. The following table shows the genera and the number of species recorded for the county : SPHAGNALES Leucobryum i Orthotrichum 5 Antitrichia . . i Sphagnum . . 6 Fissidens . . 5 Ephemerum i Porotrichium . i Grimmia 2 Physcomitrella I Leskea . i BRYALES Rhacomitrium i Physcomitrium I Anomodon I Tetraphis I Acaulon . I Funaria . 3 Thuidium 3 Catharinea . i Phascum 2 Aulacomnium 2 Climacium i Polytrichum 7 Pottia . . 6 Bartramia i Cylindrothec ium I Archidium . i Tortula . 12 Philonotis I Isothecium I Pleuridium . 3 Barbula . 10 Webera . 4 Pleuropus . I Ditrichum . i Leptodontium I Bryum . 8 Camptothecium i Seligeria . 3 Weisia . 4 Mnium . 5 Brachythecium . 7 Ceratodon . i Trichostomum i Fontinalis I Eurynchium . 10 Dicranella . 3 Cinclidotus . I Cryphasa I Plagiothecium . 2 Dicranoweisia i Encalypta . 2 Neckera . 3 Amblystegium . 3 Campy lopus . 2 Zygodon I Homalia . i Hypnum . .13 Dicranum . 2 Ulota . . 2 Leucodon i Hylocomium . 5 Five small natural orders, viz., Andreaacece, Buxbaumiacete, Spblachnacete, Timmiacece, and Hookerlaceee are unrepresented, nor, with the possible exception of Buxbaumiaceee, is it at all probable that mosses belonging to these orders will ever be added to our list. Of the 116 British genera, 55, including only a small number of species of alpine habits, are not recorded for the county. Of the six species of Sphagnum, three, viz. S. intermedium, cuspi- datum, and subsecundum, with its varieties contortum and obesum, have been found on Bricket Wood Scrubs, while four, S. acutifolium, sguarrosum, cymbifolium, and subsecundum, with its variety obesum, occur in the Lea valley. Tetraphis pellucida was discovered by Coleman in Sherrard's Park Wood, Digswell, and the rarest of the seven Hertfordshire species of Polytrichum P. urnigerum is recorded from Hitch Wood in the north of the county. The genus Seligeria, composed of minute, almost microscopic plants of chalk-loving habits, is represented by three in- teresting species, the rarest being S. pusilla, which was found growing in an old chalk-pit in Brocket Park ; S. paucifolia was discovered at one of the field meetings of the Hertfordshire Natural History Society growing upon chalk nodules in the Tunnel Woods near Watford ; and at another field meeting the third and commonest species was met with in a chalk- pit near Rickmansworth. Two species of Campylopus occur, namely C. pyriforme in Berry Grove Wood, Aldenham, and C. flexuosus noted by 64
