ADDENDA. 
I. 
On Plates xxi. and xxii. will be fouud dissections of tlie snb-genera of the Genus Hypnum (83) according to " Hobkirk'e 
Synopsis," pp. 145-182, to which the student is referred for more information than can be given here. 
83. GENUS HYPNUM, Bill. 
For descriptions of the following sub-genera of this Genus, see " Hobkirk's Synopsis," pp. 145-182. 
Sub-genus I. — Thnyidium, Schpr. (Plate xxi.). 
Species Illustrated — Thuyidium tamariscinum (Hedw.). 
Reference to Plate — a, Capsule, X 2-in. ; 6, Stem leaf, X ]-in. ; Marginal and central cells of same, X j-in. 
This sub-genus is represented in Britain by five species. 
SuB-GENUS II. — Ptychodium, Schl. (Plate xxii.). 
Species Illustrated — Ptychodium plicatnm (Schl.). 
Reference to Plate — a, Capsule, X 2. in. ; b, Stem leaf, X I -in. ; Cells of same, X i-in. 
This sub-genus is represented in Britain by one species. 
Sub-genus III. — Camptothecium (Schpr. ). * 
Species Illustrated — Camptothecium lutescens (Huds.). 
Reference to Plate — a, Capsules, X 2-in.; Stem leaf, X 1-in.; Cell of same, X i-ia. 
This sub-genus is represented in Britain by two species. 
Sub-genus IV.' — Brachythecium (Sohjir.). 
Species Illustrated — -Brachythecium rutabulum (Linn.). 
Reference to Plate — a, Capsule, X 2-iu. ; 6, Cells of leaf, X j-in. ; c, Stem leaf, X 1-in. 
This sub-genus is represented in Britain by 11 species. 
Sub-genus V. — Scleropodium (Schpr.). 
Species Illustrated — Scleropodium csespitosum (Wils.). 
Reference to Plate — a, Capsule, X 2-in.; h. Stem leaf, X 1-in.; Cells of same, X ?-in. 
This sub-genus is represented in Britain by two species. 
SuB-GENUS VI. — Eurynchium (Schpr.). 
Species Illustrated — Eurynchium crassinervum (Tayl.). 
Reference to Plate — a, Capsules, X 2-in. ; 6, Stem leaf, X 1-in. ; c. Cells of same, X i-in. 
This sub-genus is represented in Britain by 17 species. 
SuB-GENUS VII. — Hyocomium (Schpr.). 
Species Illustrated — Hyocomium flagellare (Dicks.). 
Reference to Plate — a, Capsule, X 2-iu.; Stem leaf, X 1-in.; Cells of same X j-in. 
This sub-genus is represented in Britain by one species. 
SuB-GENUS VIII. — Ehynchostegium (Schpr.), 
Species Illustrated. — Ehynchostegium confertum (Dicks.). 
Reference to Plate — a, Capsule, X 1-in. , Stem leaf, X 1-in.; Cells of same, X g-in. 
This sub-genus is represented in Britain by eight species. 
Sub-genus IX. — Thamnium (Schpr.). 
Species Illustrated — Thamnium alopecurum (Linn.). 
Reference to Plate — a. Capsule, X 2-in. ; 6, Stem leaf, X 1-in. ; Marginal cells of same, X i-in. 
This sub-genus is represented in Britain by one species. 
Sub-genus X. — Plagiotheciimi (Schj^r.). 
Species Illustrated — Plagiothecium sylvaticum (Dill. Linn). 
Reference to Plate — a, Capsule, X 2-in. ; 6, Stem leaf, x 2-in. ; c. Cells of same, X ^-in. 
This sub-genus is represented in Britain by eight species. 
Sub-genus XI. — Amblystegium (Schpr.). 
Species Illustrated — Amblystegium serjaens (Linn.). 
Reference to Plate — a, Capsule, X 2-in. ; b, Stem leaves, X 1-in. ; c, Cells of same, X ^-iu- 
This sub^igenus is represented in Britain by eight species. 
SuB-GENUS XII. — Eu Hypnum (Dill.). 
Species Illustrated — Hypnum purum (Linn.). 
Reference to Plate— a, Capsule, X 2-in.; 6, Stem leaf, X 1-in.; c, Cells of same, X ?-in. 
This sub-genus is represented in Britain by 47 species. 
Sub-genus XIIL— Hylocomium (Schpr.) 
Species Illustrated — Hylocomium loreum (Linn.). 
Reference to Plate — a, Capsule, X 2-in. ; 6, Stem leaf, X 1-in. ; c. Cells of same, X i-in. 
This sub-genus is represented in Britain by seven species. 
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