NATURAL SCIENCES OP PHILADELPHIA. 193 



On the Classification of WATER BIRDS.* 



BY ELLIOTT COUES, A.M., M.D., PH.D. 



Captain and Assistant Surgeon, U. S. Army. 



By " water birds " is meant tiie swimmers proper, as distinguislied from 

 aquatic, or even natatorial, Grallse. That the Natatores, so accepted, are one 

 of three primary divisions of birds, at least of carinate birds, is held to be de- 

 monstrable. I shall attempt the proof, and endeavor to define the natural 

 orders and families of the sub-class. I am authorized to state that the classifi- 

 cation here proposed has been adopted without modification by the Smith- 

 sonian Institution, in the arrangement of the Natatores in its museum. 



Not to allude to early classificatory schemes that the progress of ornithology 

 has shown to be impossible, nor to those late systems, based upon the inesti- 

 mrtble labors of Miiller, Burmeister, Sundevall, Gabanis and others, that relate 

 mainly to the arrangement of the higher groups, there still remain several that 

 must be taken into the present consideration. Notablj', those of Nitzsch, 

 Vigors, Bonaparte, Lilljeborg and Huxley, which bear directly upon the sub- 

 ject in hand ; notice of which is necessarj'^ before defining the modification of 

 one of them that it is the design of the present paper io establish. 



It maj' be here premised, and safely asserted, that heretofore no two orni- 

 thologists, bringing original research, and the conclusions deduced from it, 

 into action, have been able to agree closely in classification. There are as 

 many systems as there have been leaders in the science. But conflict in the 

 field of taxonomy has been chiefly along the line of the higher groups, — more 

 particularly Passeres. Respecting the Natatores, a singular unanimity has 

 prevailed in the definition of the group; and in the main, similar subdivisions 

 have been recognized, however diff"erently these have been collocated, and 

 estimated in the scale. Intermediate or " doubtful" forms are limited to two 

 or three families. Only one author stands far apart from the rest in the dis- 

 tribution of natatorial families, assigning part of them among what are known 

 as " Grallae," and the others with certain insessorial types. These facts have 

 perhaps another significance than that of simple matters of ornithological 

 record. 



Referring to the authors just mentioned, we find four principal methods of 

 primary division of birds : (I) a dichotomous arrangement in two "parallel se- 

 ries,'" based upon one physiological character, — Bonaparte; (2) a trichoto- 

 mous, founded upon very general considerations, — Nitzsch, and after him Lillje- 

 horg ; (3) a quinary, a modification of the second, by dividing two of the three 

 divisions into two each, and with minor changes, — Vigors, and manj' others ; 

 (4) another trichotomous, but from a totally diff'erent standpoint — recognition 

 of birds as modified reptiles — and carried out with special reference to one 

 anatomical character, afi'orded by certain cranial bones, — Huxley. 



After Oken's generalizations upon the condition of newly-hatched birds, 

 Bonaparte made the scheme of Altrices and Priecoces his own by strenuous, un- 

 qualified advocacy, and elaboration of details with surprising care and skill. 

 The system took strong root, and is held by many as the key-note of the 

 natural classification, comparable, in equivalency, to such profound divisions 

 as e. g., Exogens and Endogens among flowering plants, or riacentalia and Mono- 

 tremata among mammals. That the system has been unduly stretched may 

 perhaps be shown. 



Comparison, for instance, of Bonaparte's two subclasses M'ith those of pla- 

 cental and implacental mammals, may show how far the former may be 



*Con.«iderable time has passed between the preparation and the publication of this 

 paper ; in revising the proofs I have added foot-notes, where comment or explanation 

 seemed desirable, in preference to altering the original text; this is left untouched. 



1869.] 



