T. Holm — Studies in the Cyperacece. 263 



Thus with the only exception of C. lift oralis all the 

 other species are known from the arctic coasts, and as 

 stated above, C. rariflora is even circunrpolar ; it evi- 

 dently originated in the polar regions. The remarkably 

 scattered distribution of C. stygia with no intermediate 

 stations between Alaska and arctic Scandinavia is an 

 excellent example of homologous endemism, where the 

 same species seems to have originated at two points, 

 extremely remote, but, nevertheless, associated with sev- 

 eral, closely related types ; and these types are identical 

 at both stations. C. laxa shows a similar disconnected 

 distribution, being absent from northern Asia, except the 

 northeastern corner, being also absent from this continent 

 and Greenland; the occurrence of the species in Japan 

 may indicate the possibility of its existence also on this 

 continent; it closely resembles C. limosa, and may have 

 been overlooked. 



With reference to C. limosa and C. Magellanica these 

 are undoubtedly of southern origin, having reached the 

 arctic region during the glacial epoch. Regarding C. lit- 

 toral is we have in this species a genuine A m erican type of 

 very local distribution, and developed singularly distinct 

 from the other species, yet inseparable from these, to the 

 best of our judgment. 



By examining these types more closely, we shall see that 

 the general habit and structure is very uniform; indeed 

 the only characters of prominence, which appear as really 

 important from a taxonomic point of view, depend upon 

 the more dense-flowered spikes in C. littoralis, the sheath- 

 ing bracts in C. laxa, and the gynaecandrous spikes in C. 

 Magellanica. 



C. littoralis Schweinitz (Figs. 4-7). 



According to Schweinitz and Torrey 3 Car ex Barrattii 

 Schw. et Torr. is the plant named C. littoralis by Schwein- 

 itz in 1824 (ibidem). It is also the same species which by 

 Carey 4 was referred to C. fi.acca Schreb. (C. glaiica Scop). 



A very complete diagnosis and figure is given by Boott, 5 

 from which the quotation as follows : 



3 A monograph of the Xorth American species of Carex (Ann. of Xew 

 York Lyceum of Nat. Hist,, vol. 1, p. 361, 1825) . 



4 Gray's Manual of Botany, 1S57, p. 519. 



5 111. genus Carex, vol. 1, p. 69, tab. CLXXXIX. 



