196 PROCEEDINGS OP THE ACADEMY OP 



As the sura of the criticism I would be disposed to offer on Bonaparte s ar- 

 rangement, I would say : Not to refer to Rasores, Grallse and Natatores as vary- 

 ing exponents of two primes, altrices and prsecoces, but to regard the former 

 as themselves the integers, of which " aliricial " or " precocial '' are predicable 

 as exponents of modifications of which the three are alike susceptible. So, 

 therefore, altricial or praecocial Natatores, not natatorial Altrices or Priecoces.^ 



Nitzsch's earlier classificationf was a dichotomous division of Aves into 

 Carriatee aud Ratitse, after Merrem ; an arrangement that anticipated the later 

 one of Prof. Huxley in sepai-ating the struthious birds from those with a keeled 

 sternum. He afterwards J became satisfied that Strut hionidce et aff. should 

 come among Cursores, and divided all bii'ds into Av. Aerese, Av. Terrestres, and 

 Av. Aquaticm, — birds of the air, earth and water. These are difficult of precise 

 definition in terms descriptive of structural modifications, in consequence of 

 the occurrence of intermediate and aberrant forms, that furnish exceptions to 

 almost any possible diagnosis. But it comprehends a broad, well-founded 

 generalization, violates the requirements of no natural groups, and largely 

 fulfils the main conditions of a natural system. If the point be well taken, it 

 follows that birds — that Carinate birds at any rate — are modelled after three 

 types, that, however modified or even changed into Ihe semblance of each 

 other in some cases, retain definite tangible characters. Tlie system appears 

 susceptible of a crucial test. If it be true, each one of the three main stems 

 of the bird type must repeat or represent, with unquestioned fidelity, in some 

 one or more of its branches, the other two. Among the orders and families 

 into which, e. c/., Natatores are differentiated and specialized, representations 

 of Aerete and Terrestres must be found; the relationships, of course, not of 

 actual affinity, but of analogical resemblance. I think that the system will 

 stand such test, and shall in the sequel apply it in some detail. Establish- 

 ment of one of the three groups is tantamount to fixing the other two. 



Nitzsch's Natatores are a suborder Av. aquat. palmatw, as distinguished from 

 Av. aq. grallce. He adopts five "families," two of which are rather associa- 

 tions of families {Stegaiiopodes and Pygopodes). He places the Flamingoes 

 (called Odontoglossie) in Gralhc. Podoa he adds to Stcganopodes. 



The quinary system of Vigors, || in its primary divisions, is a modification of 

 the trichotomous just noticed. Disregarding subclasses, he proceeds at once to 

 five orders. The two first are a division of ^y. Aerece into Raptores and Inses- 

 iores, according as the birds are habitues of the upper air or of the trees more par- 

 ticularly, — a distinction better borne out by actual structure of the birds than 

 bj' reference to this assumed difference. Nitzsch's two divisions of Av. aq. 

 Grallce and Palmatai give, with scarcely a variation. Vigors' two last orders 

 GraUa/ores and Natatores. Vigors' middle order, Rasores, comprehends galli- 

 naceous birds and pigeons. That these divisions are in the main strictly natu- 

 ral, is probably not open to serious question. A chief defect is in theinequiva- 

 lency of the five orders. Thus Rasores contains types more dissimilar from each 

 other than Raptores are from (other) Insessores ; and this, too, without taking 

 Ratitm into consideration. If he would make ordinal distinction of Raptores 

 and Insessores, pari passu he should have separated Columhie from Galliiice. His 

 Insessores, again, contain types as mutually dissimilar as either of them are 

 from Raptores. Without opening here the question of Ratilcc, nor of recogniz- 

 ing, aside from ostriches, groups higher than orders, it may be said that this 

 system requires modification in the adoption of several more orders, — his Ra- 

 sores and J?i.sessores especially demanding dismemberment into two or three. 



* In this discussion of Bonaparte's scheme, it might be objected that I galvanize a dead 

 body in order to kill it over again. But doubtless my objectors can call to mind several 

 signal instances where, within the last few years, Bonaparte's system has been accorded 

 the importance which is here criticised. 



fObserv. de Av. Art. Carot. Comm. 1829. 



X Pterylographie, etc., 1840. 



II Obs. on the Nat.Atfin. that connect Ord. and Fam. of Birds. Trans. Linn. Soc.xix, 1827. 



[Dec. 



