Of the Liverworts (Hepaticae) forty-four species are known to occur; and the Stoneworts (Characeae) are represented by seven species—­two of Chara, two of Tolypella, and three of Nitella.

The Algae have been pretty fully investigated, especially the Diatomaceae, of the 252 species of Algae known to occur in the county, 156 belonging to that interesting family of microscopic plants.  As an illustration of their minute size it may be mentioned that a single drop of water from the saucer of a flower-pot at Hertford, mounted as a microscopic slide, was found to contain 200,000 separate frustules of Achnanthes subsessilis, and it was estimated that these occupied only one twenty-fifth part of the drop.  Both species of Chlamidococcus (the old genus Protococcus), C. pluvialis and C. nivalis occur; and the pretty Volvox globator has frequently been found.

Of the Lichens much less is known, only sixty-seven species having been recorded.  The most noteworthy are Calicium melanophaeum, found on fir-trees in Bricket Wood; Peltigera polydactyla, on moss-covered ground in Oxhey Woods, Watford; Lecanora phlogina, in the Tunnel Woods, Watford; and Pertusaria globulifera, on trees in the same woods and also in Bricket Wood.  As woods in the vicinity of Hertford and of Watford only have been searched for lichens, our list ought to be largely increased by investigation in other parts of the county.

Of the Fungi our chief knowledge is derived from lists of species collected at Fungus Forays of the Hertfordshire Natural History Society and from records of the Mycetozoa by Mr. James Saunders.  The number of species recorded for the county is 735, of which fifty-eight are “myxies”.  Of the Hymenomycetes, or mushroom-like fungi, some very noteworthy finds have been made, nearly all at Forays of the county society.  They include two species new to Britain, viz., Agaricus (Nolania) nigripes, found in Aldenham Woods, Watford, and Ag.  (Hypholoma) violacea-ater, in Gorhambury Park, St. Albans (by the present writer).  Hertfordshire has also furnished the second British records for Ag. (Lepiota) gliodermus (Broxbourne Woods), Ag.  (Leptonia) euochrous (Ashridge Woods), Ag. (Psathyrella) aratus (Sherrard’s Park, Welwyn), and Paxillus Alexandri (Hatfield Park), this species having first been recorded from Hatfield Park, Essex; and the second and third British record for Agaricus (Clytocybe) Sadleri (Ashridge Park and Cassiobury Park).  The very rare Strombilomyces strombilaceus has been found in Grove Park, Watford, and the still rarer Peziza luteo-nitens on the Chalk slopes between Aldbury and Ashridge Park.  Lastly it may be mentioned that Mr. Saunders added the “myxie” Physarum citrinum to the British fungus-flora from specimens found by him at Caddington and Welwyn.