24 INTRODUCTION 



near Beacon Hill at that time. Some have since spread from the 

 true pine-barrens, but, as shown in paragraph 29, this was to be 

 expected. The list of these northern species follows: 



Scheuchzeria palustris, Mitella diphylla, 



Panicularia obtusa, Nemopanthus mucronata, 



Carex exilis, Zizia aurea, 



Malaxis unifolia, Gentiana crinita, 



Anemone canadensis, Aster nemoralis. 



37. There are doubtless other species and the same phenomenon 

 has been noted by entomologists. Professor Smith writes of 

 Trechus chalybeus, and a few other insects, "that the only trace of 

 real boreal species has been found in the deep cold swamps (bogs) 

 of Ocean County." 



38. In this connection the distribution of the most remarkable 

 plant of the pine-barrens, Schizaea pusilla, is very interesting. It 

 is found only in the pine-barrens and in Nova Scotia and New- 

 foundland, and is unknown between these points. If Dr. Scharff's 

 recently proposed theory* that perhaps parts of Nova Scotia 

 and Newfoundland remained unglaciated through all the period 

 of the Pleistocene is correct, then it is not impossible that Schizaea 

 is a relict in the pine-barrens of its southern migration, and that 

 it is also a relict in the north, all the intervening territory having 

 been preempted first by the ice, secondarily by more "aggressive" 

 plants after the recession of the ice. This is little more than 

 interesting speculation, but Scharff, whether wrong or right in his 

 contention, has opened up a wide field of discussion. It is cer- 

 tainly significant that Schizaea is not found in the unquestionably 

 glaciated country, and is found only in the pine-barrens and in the 

 [probably] unglaciated northeast. An almost similar distribution 

 is that of Aster nemoralis, which is lacking in the intervening 

 territory between its northern outposts in northern New York 

 and Newfoundland and its southerly stations in New Jersey. All 

 of these evidences — the geological history of the country, the isloa- 



* Scharff, R. F. Distribution and origin of life in North America. New York. 

 1912. For further data on this point see also Adams, C. C. The Post-glacial dispersal 

 of the North American Biota. Rept. Int. Geog. Cong. 8: 623-637. 1904. Allan, J. A. 

 The geographical distribution of N. Am. Mammals. Bull. Am. Museum Nat. History 

 4: 199-243. 1892. Transeau, E. N. On the geographic distribution and ecological 

 relations of the bog-plant societies in N. Am. Bot. Gaz. 36: 401-420. 1903. 



