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moss which is recognizable almost at a glance, grows luxuriantly 

 in a bog at Salisbury but is reported from only six other North 

 American localities, the nearest of which is more than 250 miles 

 away. Another Connecticut moss, Claopodium pellucinerve, is 

 apparently known elsewhere only from Yukon Territory and 

 northern India. But even more puzzling are those cases where 

 two species reach respectively their northern and southern limits 

 at one and the same station. Three instances of this sort occur 

 to the writer. In 1892 two ferns, Cheilanthes lanosa and Crypto- 

 gramma Stelleri, were collected on West Rock, a trap ridge near 

 New Haven, where they grew side by side in crevices on the 

 precipitous face of the rock. The first named species is widely 

 distributed in the southern United States, but is unknown else- 

 where in New England, the nearest recorded stations being along 

 the Hudson River, more than 60 miles distant. The latter 

 species is a northern calcicolous form which also occurs locally 

 in the northwestern part of the state. Owing to the inaccess- 

 ability of their eerie no one in recent years has ventured to 

 ascertain whether this interesting station still exists. In a 

 similar manner two mosses, Pogonatum brachyphyllum and 

 Aulacomnium androgynum — the former a coastal plain form not 

 otherwise reported north of southern New Jersey, the latter a 

 boreal species which until recently had never been collected 

 south of northern Massachusetts — grow on granitic ledges along 

 the shore of Long Island Sound at stations less than a mile apart, 

 while the two liverworts, Anthoceros Macounii and Ricciella 

 membranacea, reach respectively their southern and northern 

 limits in central Connecticut, where at Hartford they grow 

 intermixed in the same ditch. No attempt is made to explain 

 such anomalous vagaries of distribution. It would almost seem 

 that the caprices of chance had overridden the natural laws of 

 dissemination, and while edaphic factors may doubtless account 

 for the persistence of a plant after it has once become established 

 it is difficult to reconcile such antithetical associations as the 

 last three above noted. 



The chief factors which to-day control the distribution of the 

 vegetation within the state may be summed up under two heads : 



