REVIEW OF BIRDS. 439 



among the Aquaticse, and in considering the Struthionine hirds a distinct grotip 

 from the other three. 



There is, as far as experience yet extends, a very remarkable correspondence 

 between the natiu-e of the upper wing-coverts and of the carotidcs communes, 

 which adds to the importance of both these characters, which have generally 

 been but little obsei-ved. All those birds that have the large upper wing-coverts 

 of the first row on the cubitus so short that they do not reach beyond the middle 

 of the cubital quills, have only one carotis communis, viz., the sinistra. Those 

 birds ia which the above-mentioned wing-coverts form several rows and extend 

 beyond the middle of the cubital quills, have, on the contraiy, generally two 

 carotides communes, viz., one dextra and one sinistra. The only exceptions to 

 this rule are Cypselus, Trockilus, Merops, one or a few species of Psittacus, 

 Kliea, PJicBnicopterus, Podiceps, and Pclecanus, which, although belonging to 

 the latter category in regard to the wing-coverts, yet have only one carotis com- 

 munis. This is the dextra in Phoinicopterus. We do not, therefore, hesitate 

 to consider these two characters to be among the most important in judging of 

 the affinity of the birds ; and they show with certainty that the birds of prey 

 have not their place at the beginning or at the end of the system. 



The Strisores, one of the twelve orders in which we have arranged the class 

 of birds, includes several birds that we formerly considered should belong to the 

 Passeres, from their near correspondence in form with the latter. But as they 

 deviate from them in regard to the upper wing-coverts and the claw of the hind 

 toe, and sometimes even in regard to the carotides communes, we are of opinion 

 that they should be regarded as belonging to a different order. They have 

 been separated from the Passeres by Sundevallt and by Nitzsch; and the fonner 

 has arranged them under the order Coccyges, v/hich, according to him, also in- 

 cludes the Zygodactyli and ColumhcB. They are, however, distinct from the 

 Zygodactyli in the nature of then- feet, and cannot be arranged under this order 

 without depriving it of its most distinguishing character. Tbey seem also to 

 cause confusion if they are arranged within either of the orders Passeres or 

 Zygodactyli ; and we have therefore considered it right to arrange them as a 

 distinct order — Strisores, which name was given to them by Cabanis in 1S47. 

 However distinct they seem to be, as well from the Columbine section and the 

 birds of prey as from the Zygodactyli, it is very difficult to find any character 

 that sharply and distinctly distinguishes them from these three orders ; and we 

 have been compelled to use a character in the scheme that does not belong to 

 all, although the majority of them possess it. They appear to be mi interme- 

 diate group between Accipitres, Zygodactyli, and Passeres. 



The order Longipennes has generally had a very changeable place in the sys- 

 tem, sometimes the first among the swimmers, sometimes the last. When the 

 swimmers are, as here, arranged in two groups according to the form of the 

 beak, their place is, as will be seen from the scheme, unquestionable, as we of 

 course must begin with the Pygopodes. The Longipennes approach these very 

 nearly in the genera PufjimLs and Halodroma. Pnffinus has, together with 

 (Jolymlnis and Podiceps, a long pyramidal erect process at the upper end of the 

 tibia, and the tarsi are compressed like theirs. The genera -Phalacrocorax and 

 Mergus form an intermediate link between the Steganopodes and the Lamel- 

 lirostr^s. 



First Division or Sab-c!ass< 



Natatores, Illiger; SundevalL 



Upper part of the eras (tibia and fibula) not free, but drawn in within the 

 skin that covers the body.* The basis of the hind toe above that of the ante- 



t Kongl. Vetensk. Acad. Handl. 1843, pp. 375 and 376. 



* Some of the Longipenues are said to form au exception to this. 



