?TO Trotter on the Genus Helminthophila. [October 



bers, though not directly apparent in all the species, is expressed 

 by the curious phenomena which have lately come under our 

 notice. Bachmani is exceedingly rare, for aught we know on 

 the verge of extinction, though it still exists in favorable localities 

 in the vast swamps of the Southern States. 



The mythical carbonata might have been the last of another 

 form, — who can tell? Audubon gave it a place in this genus. 



Chrysoptera and pinus yet remain fairly abundant but forced 

 apparently to cross with each other, and the resulting forms, 

 la-jorencei and leucobronchialis, without doubt recross with the 

 parent species.* Further, we find evidence that pinus has un- 

 doubtedly gone over to the strange genus Oporornis and con- 

 tracted an alliance there. f 



These are the facts, and we are left to draw our own conclu- 

 sions in the best way possible. Genera and species rise up, in- 

 crease and become dominant only to break down again under the 

 pressure of other and better adapted forms. What the other 

 genera of the Mniotiltidae may have been in the past we can only 

 surmise. 



Those that now possess but one or two species ma} 7 , and very 

 likely have, possessed more and been dominant in their time. A 

 change in habit under pressure and consequent structural modi- 

 fication would be of immense advantage, and finally result in one 

 or two well adapted species forming a well defined genus. Such 

 may have been the history of Mniotilta, Proto?iotaria, and others, 

 and such may be the future of these Helminthophilce who now, 

 as it seems to me, show unmistakable evidence of break-down 

 after a long and severe struggle against better adapted forms. 



This or ultimate extinction are the only alternatives. 



* Brewster, Wm. Bull. Nutt. Ornith. Club, Vol. VI, Oct. 1881, p. 218. 



t Langdon, Frank W. Bull. Nutt. Ornith. Club, Vol V, Oct. 1880, p. 208, plate, iv. 



