361 



ON SCHI8TOSTEGA OSMUNDACEA MOHR. 



By G. T. Harris. 



{Read March I2th, 1918; communicated by the Hon. Editor.) 



Plates 23 and 24, and Figures 1-3 in Text. 



This moss was originally described and figured by Dickson in 

 1785 (1), and named by him Mnium osmundaceum. Later, in 

 1803, Molir instituted the genus Schistostega for it, restoring 

 Dickson's specific name of osmundacea which had been super- 

 seded by Ehrart and by Hedwig (2). Sir J. E. Smith in his great 

 work on English plants (3) followed Hoffmann's lead of placing 

 it in Hedwig's genus Gymnostomum, presumably on account of its 

 gymnostomous capsule. Hooker and Taylor (4) accepted Mohr's 

 genus but adopted Hertwig's specific name of pennatum. Bridel 

 {5), Bruch and Schimper and Giimbel (6), Wilson (7) and Berkeley 

 {S) all adopted Mohr's nomenclature, and as Braithwaite (9) and 

 Dixon (10) among modern bryologists confirm these previous 

 authors by themselves accepting Mohr's genus it may be taken 

 that finality has at length been reached. 



It is the only species of its genus and order. 



The plant upon which Dickson's original description was based 

 was collected in Devonshire, in the much-quoted station " in 

 via ducente a vico Zele ad templum South Tawton, circiter 4 

 milliaria ab Okehampton, in comitatu Devoniae." As I know this 

 particular lane quite well I am able to state that it is just such a 

 locality as Schistostega best thrives in. Mr. W. P. Hiern, F.R.S., 

 who has very kindly sent me Dickson's original description and 

 much information relative to its early history, writes, " The 

 collector was Sampson Newbery of Zele in the parish of South 

 Tawton., Devon." As late as 1830, the date of the seventh 

 edition of Withering's Arrangement of British Plants (11), only 

 Devonshire localities are given, viz. the one just mentioned, one 



