TOD US. 161 



named, is pre-eminently typical ; and we shall find, 

 upon close analysis, that the variation of its species, 

 as in the sub-genus Bos*, turns out to be regulated 

 by the very same law ; they actually become types 

 of form. And we shall find these types almost as 

 distinctly marked as if they belonged to a family, 

 instead of merely representing the succession of 

 species in a sub-genus. 



The most universal character of the typical todies 

 is their flat elongated bill, in opposition to that of 

 Platyrhynchiis, which, although equally flattened, 

 is remarkably short ; the sides are bristled, but 

 these bristles are short and weak, and in some species 

 are almost obsolete. The wings and tail are short, 

 but the latter is much more conspicuous than in 

 Platythynchus, while the form of its termination 

 indicates the variation of the species and the posi- 

 tion they occupy in the series. Thus, in the Todu* 

 clridis the tail is even, in melanocephalus^ it is gra- 

 duated, in mcgacei>halus J it is shortest, and the ei;d 

 is rounded ; while in platycircus it is longest, with 

 the feathers broad, but terminating in points. The 

 other species yet discovered fill up the intervals, and 

 arrange themselves close to one or other of those 

 just named. The variation in the length and struc- 

 ture of the feet is no less remarkable. These 

 members are always sufficiently long to point out 

 the sub-genus ; their vaiiation is consequently com* 



* Clnssif. of Quadrupeds, p. 281. 

 t Spix Av. Nov. ii. pi. 9, f. 2. 

 Ornitli. Drawings, pL 



