146 Mr. Swainson on two nero Genera of Birds. 



The FormicivoroB or Ant-Wrens, are all of them very small ; 

 and in an artificial arrangement might very well be associated 

 •with the Warblers. In all but their slender bill, they present a 

 perfect miniature resemblance to the true Thamnophili, even to 

 the lateral scales of their tarsi, which are small and numerous. 

 They dilFer from the Drymophilce by their comparatively short 

 legs, which are obviously not intended for walking. We know 

 little of their natural economy, further than that they frequent 

 bushes and the low branches of trees,which they probably cleanse of 

 those small insects, passed over by their more powerful brethren. 



I should have had some hesitation in placing this group of little 

 birds, so near to that which comprises the powerful Thanmophilt, 

 but for the figure and description of the Fourmilier tachet^ given 

 in the Planches Coloriees, PI. 179, f. 1.2. It will be perceived 

 that in the series of Thamnophili described in the last number of 

 this Journal, the species are characterized by a shorter and more 

 rounded tail, and that they gradually diminish in size until we 

 reach T.ferrugineus, which is less than a Sparrow. The Four- 

 milier iachet is even smaller ; yet, in its strong and compressed 

 bill, and short rounded tail, it exhibits the two most prominent 

 characters of the lesser Thamnophili. To that group it may, there- 

 fore, safely be referred. 



On the same plate is figured another bird, (also referred to the 

 genus Mj/othera,) by the name of Fourmilier gorgeret. It is of 

 the same size as the last, but with a bill much more slender, and, 

 to all appearance, perfectly agreeing with that of Formicivora. 

 Here then we may fairly presume that the passage from one 

 group to the other takes place. 



We cannot be sufiiciently thankful to M. Temroinck, (however 

 the above inference may militate against his own particular views) 

 for having furnished us with the means of tracing one of those 

 beautiful gradations, by which natural groups are insensibly 

 united. 



The short tailed Thamnophili may perhaps hereafter be found 

 sufficiently numerous to constitute a separate genus ; but in our 

 present state of knowledge, they may be considered as forming 

 only a sectional division. 



