IT2 THE BOG-MOSSES OF ESSEX. 



The author, no doubt, had in mind the recent changes in the 

 classification of these organisms, which share with other large 

 and widely spread genera, such as Rubies, Rosa, and Hieracium 

 among land plants, and Potamogeton, the Batrachian Ranunculi and 

 the Harpidioid section of Hypnum among aquatics, that difficulty 

 of classification which arises from the presence of only very 

 slight differences and very great likenesses between the forms. 

 This characteristic aggravates the question as to what is a 

 species and causes great differences of opinion among workers 

 in these groups. 



In the following list the system of Warnstorf has been 

 followed. 1 This system has been adopted by most Continental 

 and American writers, and in some of the more recent local 

 lists of Sphagna in this country. 2 According to Warnstorf's 

 classification 41 species of Sphagna occur in this country, while 

 only 12 are recognised in the most recent book on British 

 mosses. 3 This classification is based largely upon the position 

 ot the chlorophyllose cells in the branch leaves and the 

 distribution of the pores in the hyaline cells, and is therefore 

 to some extent ah artificial one, but the forms so distinguished 

 ■do, as a rule, according to my experience, correspond with what 

 appears to be a natural grouping of the plants themselves. (But 

 see note under Sphagna subsecunda below.) 



Several lists have been published. I have been able to find 

 the following : — 



(1) 1845. Greenwood, A. " Mosses found near Chelmsford." 



Phytologist, Vol. ii. 



(2) 1872. Parsons, Dr. A. F. " Mosses of London District. " 



Science Gossip, Vol. viii., p. 64. 



(3) 1884. English, J. MS. list of Mosses of Epping Forest. 



(4) 1890. Buxton, E. N. " Mosses." Epping Forest, Ed. III., 



PP- l S5i 136. 



(5) 1891. Makquand, E. D. ''List of Mosses in Mr. E.G. Varenne's 



Herbarium." Essex Naturalist, Vol. vi., pp. 33. 



(6) 1900. Horrell, E. C. " European Sphagnaceas." Journal of 



Botany, 1900. 



(7) 1901 ? Dixon, H. N., MS. list of N. Essex mosses. 



(8) 1903. Shenstone, J. C, Victoria History of Essex. Article 



" Botany." 



1 Horrell, E. C, " European Sphagnaceas," Journ. of Bot., 1900. 



2 e.g., Ingham, W., " Sphagna of Yorkshire and Durham." Journ. 0/ Bot., 1901., p. 145. 



3 Dixon, H. N. Student's Handbook of British Mosses. Ed. II. (1904). 



