ON THE FLORA OF SHETLAND iii 



have relied almost entirely on Mr. Linton's notes, not being 

 myself sufficiently well acquainted with the characteristics of 

 the types ; while Mr. Linton also rendered special assistance 

 in connection with H. trimcatum. For my own satisfaction 

 I have confirmed Mr. Linton's observations, and have 

 re-examined the various forms both microscopically and 

 otherwise. 



In the "Botany of the Faeroes" (Part II., 1903) Mr. 

 Hugo Dahlstedt has given an interesting and exhaustive 

 account of the species at present known, from which it 

 appears that those islands possess twenty-three forms, of which 

 two are varieties, while in Shetland we have eighteen forms, 

 of which four are varieties. The following table shows the 

 relative distribution of the various groups. The numerals in 



From this comparison it appears that Shetland, with its 

 far greater diversity of rock formation, possesses five forms 

 less than the Faeroes ; on the other hand, seven groups and 

 sub-groups are represented in Shetland against five in the 

 Faeroes, a circumstance which may possibly have some con- 

 nection with the same feature. Whether we consider the 

 number of forms occurring or the great abundance of some 

 of those forms, the Alpestria are beyond question the 

 dominant group in Shetland ; and it is very remarkable that 

 the Cerinthoidea, the dominant group in the Faeroes, and re- 

 garded by Dahlstedt as an essentially Atlantic type, should 

 be quite wanting in Shetland, although sparingly represented 

 in the Orkneys. Mr. Dahlstedt remarks {I.e. p. 627) that 

 the Cerinthoidea are " met with dispersed over the Shetland 

 Islands"; but I think that he must have been misinformed on 



