﻿GATES— PAIRS OF SPECIES 



gheniensis. Only if the distributions were reversed would it 

 appear probable that R. allegheniensis had given rise to R. aboriivus, 

 through a negative mutation in the nearly complete loss of the 

 beak. 



ACTAEA ALBA (L.) MlLL. AND A. RUBRA (AlT.) WlLLD. 



In the genus Actaea the species are all remarkably similar in 

 foliage and habit, almost the only sharply contrasting characters 

 being found in the thickness of the pedicels and the color of the 

 berries. All the American forms were formerly treated as varieties 

 of the European A. spicata L., but it has become customary to 

 treat them as species. A. alba and A. rubra constitute a con- 

 spicuous pair of these species in eastern North America. They 

 have both been considered varieties of A. spicata, but are no doubt 

 worthy of specific recognition. We may first compare them, and 

 then we shall rind it profitable to examine the whole genus Actum. 



acutish 



Petals rhombic-spatulate, 

 much shorter than tli 



ting pedicels thick 



A . rubra varies in foliage from forms scarcely if at all distinguish- 

 able from the typical A. spicata, to forms having larger, coarsely 



