_Classification._--On this I have fully treated elsewhere ("The Moss World," 'Popular Science Review,' Oct., 1871), and it may suffice here simply to indicate the families of British mosses and their mode of arrangement. The cell-texture of the leaf takes an important place in the characters, and in accordance with this principle the Cleistocarpous or Phascoid group is broken up and distributed in various families. We have two orders; one indeed, comprising only the genus _Andreæa_, is distinguished by the capsule splitting into four valves united at apex; the other, including the bulk of the species, has in most cases a lid, which separates transversely, and usually discloses a peristome of tooth-like processes. The structure of these teeth again enables us to form three divisions. In the first they consist of a mass of confluent cells; in the second, of tongue-shaped processes, composed of agglutinated filaments; and in the third, of a double layer of cells, transversely articulated to each other, the outer layer composed of two rows of firm coloured cells, the inner of a single series of vesicular hyaline cells, on which the hygroscopic quality of the tooth depends. Sub-Class SPHAGNINÆ. Bog Mosses. Fam. 1.--Sphagnaceæ. Sub-Class BRYINÆ. Frondose Mosses. Order 1.--Schistocarpi. Fam. 1.--Andreæaceæ. Order 2.--Stegocarpi. Div. 1.--Elasmodontes. Fam. 2. Georgiaceæ. Div. 2.--Nematodontes. Fam. 3.--Buxbaumiaceæ. Fam. 4.--Polytrichaceæ. Div. 3.--Arthrodontes. Subdiv. 1.--Acrocarpici. *Distichophylla. Fam. 5. Schistostegaceæ. | Fam. 6. Fissidentaceæ. **Polystichophylla. Fam. 7. Dicranaceæ. | Fam. 12. Splachnaceæ. " 8. Leucobryaceæ. | " 13. Funariaceæ. " 9. Trichostomaceæ. | " 14. Bryaceæ. " 10. Grimmiaceæ. | " 15. Mniaceæ. " 11. Orthotrichaceæ. | " 16. Bartramiaceæ. Subdiv. 2.--Pleurocarpici. Fam. 17. Hookeriaceæ. | Fam. 20. Leskeaceæ. " 18. Fontinalaceæ. | " 21. Hypnaceæ. " 19. Neckeraceæ. | Sub-Class HEPATICINÆ. Liver Mosses. Fam. 1. Jungermanniaceæ. | Fam. 3. Anthocerotaceæ. " 2. Marchantiaceæ. | " 4. Ricciaceæ. Among species which may be generally met with by beginners on the look-out for mosses, we may enumerate the following: _On Walls._--Tortula muralis and revoluta, Bryum capillare and cæspiticium, Grimmia pulvinata, Weisia cirrhata. _In Clay Fields._--Phascum acaulon, Pottia truncatula and Starkeana.