HELMET CURASSOW. 185 



found among those quadrupeds which belong to the 

 ruminating order. This analogy we have so amply 

 and repeatedly verified in our former volumes^ that 

 nothing more need be said upon the subject in this. 

 In enumerating the five types of the genus Crax *, an 

 experienced ornithologist will perceive that^ without 

 exactly designating them as representatives of the five 

 types of the Animal Kingdom, we have so arranged 

 them that the series form a circle, — Craa^ being the first, 

 and Lophocerus the last : hence it results, that, if Crax 

 be the pre-eminently typical, Lophocerus must be the 

 rasorial. Now^ this is borne out in a remarkable manner 

 by the structure, both external and internal, of the 

 latter. Lophocerus has the outward form of the rasorial 

 type in its helmet-like bill ; and it has that peculiar 

 developement of the windpipe, which is not only an 

 indication of the same type, but is a character also 

 which brings it into immediate junction with Crax 

 Alector, — the only two birds of this circular group 

 which anatomists have yet discovered to possess this 

 particular formation : thus is the circle of the Cracidce 

 classed. Bnt another affinity of equal importance results 

 from this view of the subject. The CracidcB and the 

 PavonidcB, as we have elsewhere shown, blend into each 

 other ; but the difficulty has hitherto been where to 

 find the links of connection. A careful analysis of the 

 two groups, undertaken with the sole object of ascer- 

 taining this question, showed us that, in the series of 

 forms among the rasorial groups, no birds came so near 

 to the Lophocerus galeata, as those of the genus Numida, 

 or Guinea-fowls : these have been placed by all writers 

 close to the turkeys ; and the Honduras turkey is so 

 close to the genus Pavo, that it actually seems half a 

 peacock. The series, therefore, between the Cracida^ 

 and the FavoyiidcB being so obviously complete, it follows 

 that the five great divisions of the whole order Rasores 

 constitute a circle, of which the helmet Guinea-fowl is 

 the first link, and the helmet curassovv is the last. AVe 



* Classification of Birds, ii. 352. 



