834 OBSERVATIONS ON A SPECIMEN OF " SULA BASSANA." 



we might expect to see exhibited throughout the animal kingdom. It 

 is only by the more modern systematists that families and sub-families 

 have been interposed between the order and the genera, (^uvier and 

 Vander Hoeven each admit four great families of Natatores, Palmi- 

 pedes or Anaeres, as the order has been named by different writers. 

 Cuvier gives them as the Divers ( Brachypteres) ; the Gulls and their 

 allies including the Petrels {Longipennes) ; our PeJecanidae, called by 

 Cuvier Totipahnati ; and the Ducks and Geese (^Lamellirostres.) 



Vander Hoeven, with a slight difference in the order of the series 

 and in the naming, gives: 1. Brevipennes or Urinatores ; 2. Ducks 

 {LamelJoso-deniati) ; 3. Steganopodes (Illiger's name for the TotU 

 palmati of Cuvier), the Pelicans ; and, 4. Longipennes, the Gulls, 

 Terns, and Petrels. 



Dr. George Gray, following Vigors, Swainson, and others, separates 

 the Auks and Penguins (his family Alcidae) from the Divers, Colym- 

 bidae. Prince Bonaparte considers the Penguins, Spheniscidae, as 

 being also distinct ; and he, as well as Gray, separates the ProceU 

 laridae from the Gulls and Sea Swallows. Thus Prince Bonaparte 

 receives seven. Dr. Gray six, Swainson five, and other great authorities 

 only four principal families of Natatores. In my view of the sub- 

 ject, the difference between Alcidae and Colymbidae is well established ; 

 but Spheniscidae (the Auks of the southern hemisphere) are to be 

 accounted only as a sub-family ; whilst I think both the Petrels and 

 ferns only sub-fam.ilies of Laridae, 



It appears to me, in short, that, putting his theory out of view, 

 Mr. Swainson has here exercised a wise discretion, recognizing a mani- 

 fest distinction of structure and habits, but refusing, where there are 

 very strong points of general resemblance, to make minor differences a 

 pretence for multiplying families. Let us now ask whether we can 

 perceive among the families of Natatores or swimming birds, any 

 thing like representation of the several tendencies of development 

 which have been pointed out as occurring in the various divisions of 

 the animal kingdom. 



The character of power and of the highest development suited to 

 the type is in the outer circle of birds exhibited by the order of Rap- 

 tores, the birds of prey. We have then to observe whether any of 

 our Natatorial families displays characteristics analogous with these 

 birds. We might look especially to strength of wing, rapidity of 



