428 Mr. N. A. Vigors on the Natural Affinities 



Their mode of seizing their prey is conformable to these cha- 

 racters : they receive it in full flight into the cavity of their 

 mouths, which remain open for that purpose, and where a vis- 

 cous exudation within, and a strong reticulated fence of vibrissa 

 on the exterior, assist in securing the victim : while, on the 

 other hand, the longer-billed families catch their food by their 

 bills. The series of succession in the tribe may be stated* as 

 follows, the typical families being placed in the centre : 

 ,-t-rf, Meropida. 



HirundinidcB. 



Caprimulgida. 



TodidcE. 



HalcyonidcB. 

 The family of the Meropidce, to which we may first turn our 

 attention, as that group of the present tribe, which by the length, 

 slenderness, and downward curvature of the bill, is most nearly 

 connected with the conterminous tribe of Tenuirostres, exhibits 

 at first sight a decided discrepancy with the succeeding family 

 of Hirundinida, where the bill is short and wide : and if we 

 examine only the typical species of each, we must admit that, in 

 respect to these particulars, there is a manifest distinction be- 

 tween them. Independently, however, of the general characters 

 in which both families approach each other, such as the breadth of 

 the rictus of the bill, the short and feeble legs, the strength of the 

 wing, and the consequent habit of using that member chiefly in 

 seeking their support, — we find a gradual approximation take 

 place even in their bills : those of some of the extreme species of 



* Or thus, with reference to their typical and aberrant characters : 



Normal group. 



Rostris brevibus, debilioribus, ad f HirundinldtE. 



captandum baud idoneis . . J_ Caprimulgidm. 



Tyjncal group. r TodideC. 



Rostris longis, fortioribus, ad cap- J Halcyonida. 



tandum idoneis 1 . 



L Meropida, 



Merops 



