HISTORICAL SURVEY OF LICHENOLOGIC AL WORK IN THE ANTARCTIC 9 



St. 33. Island in lat. 63° 45', long. 58° lo'. 

 St. 34. Headland in approx. lat. 63° 49', long. 58^ 20'. 

 St. 38. Islet in approx. lat. 63° 58', long. 58^ 36'. 

 St. 46. Islet in approx. lat. 63° 59', long. 57" 23'. 

 St. 48. Projecting headland on south side of Vega Island. 

 St. 51. Site of camp on shore of James Ross Island in Sidney Herbert Sound. 

 St. 52. Valley on coast of James Ross Island in Sidney Herbert Sound. 

 St. 62. A concealed fresh-water lake on the west side of James Ross Island. 

 St. 66. Headland on James Ross Island, west side, in Rohss Bay. 



St. 73. Headland (perhaps formerly islet) adjoining the Naze, north coast of James Ross Island. 

 St. 75. Locality on James Ross Island on the west side of the bay forming the southern extension of Sidney Herbert 



Sound. 

 St. 77. Headland in approx. lat. 63° 38', long. 57" 08'. 



GEOGRAPHICAL DISTRIBUTION 



It has long been known that the antarctic flora includes a considerable bipolar element, consisting of 

 species which occur also in the Arctic (with or without outlying occurrences at high altitudes in the 

 temperate northern hemisphere). The phenomenon has been fully treated in a recent paper by Du Rietz 

 (1940). Whether these species have originated in the Arctic and spread across the equator to the 

 Antarctic, or vice versa, is a matter for surmise. Du Rietz (1929) is of the opinion that the area of 

 greatest specific difl^erentiation of a genus is most likely to be that in which it originated. If this is so, 

 then certain predominantly antarctic and subantarctic bipolar lichen genera, such as Sphaerophorus , 

 Placopsis and Neuropogon, must be of southern origin. In the Antarctic, the bipolar element is much 

 more strongly represented in the Graham Land region than in the Ross Sea sector, the only other area 

 of which the lichen flora is sufficiently well known to permit of any comparison. This may be due to one 

 or both of two factors : (a) the lesser distance separating the Graham Land sector from the adjacent 

 land masses ; and (b) the existence of a more continuous montane pathway of migration, along the 

 Cordilleran chain and the Rockies, than is available in the eastern hemisphere. There is actual evidence 

 of Cordilleran migration in the case of Neuropogon siilphureus (Lamb, 1939). Among the antarctic 

 Pyrenocarp lichens, the delimitation of the term ' bipolar ' presents some difficulties. At one end of the 

 scale there is Mastodia tesselata, very strictly bipolar in its distribution (subantarctic and antarctic 

 southern hemisphere, arctic eastern Siberia). Dermatocarpon intestiniforme is a good representative of 

 those bipolar species which also possess an outlying alpine areal in the temperate northern hemisphere. 

 Of the marine species, Verrucaria ceiithocarpa can be regarded as bipolar, although it penetrates 

 into temperate Europe and North America; with the other species, V. maura, V. microspora and 

 V. mucosa, the extension into the temperate zone is so marked that the term ' bipolar ' becomes hardly 

 applicable. 



Species apparently endemic to the Graham Land peninsula and adjacent islands are V. cylindrophora, 

 V. dispartita, V. elaeoplaca, V.fameUca, V.psychrophila, V. Racovitzae, V. serpidoides and Microglaena 

 afitarctica. The only Pyrenocarp lichens known to date from the Ross Sea area^ are Thelidium 

 maequale and Th. parvum, both endemic to that region. 



Apart from the doubtful record of the genus Endocarpon by Darbishire (1910). 



1R 



WOODS 

 HOLE. 



