154 MR. W. K. PARKER ON THE OSTEOLOGY 



skull, in each of the smaller groups of genera, but even in the structure of the 

 adult. 



An equally large field awaits the labourer lower down among the feathered tribes. Who 

 will trace for us the relationships of the border-groups of the " Grallatores " and 

 " Palmipeds," and tell us how much of isomorphism and how much of affinity there is 

 between the Phalarope, the Coot, and the Grebe ? It is worth while to notice that the 

 Coot (Fulica atra) is thicker in body and has a much softer and fuller plumage than 

 its inland relatives ; it is also more marine in its habits. A Coot with a still thicker 

 body and shorter sternum would make a very apt connecting link between Fulica atra 

 and the small short-bodied Grebe {Podiceps {Sylbeocyclus) europ(Eus)\ 



The nearness of the Gulls to the Plovers is indicated by the Pratincole, which con- 

 nects the Plovers and Oystercatchers with the smaller species of the family " Larinse." 

 The Grebes {Podiceps), the Divers (Colymbus), and the " Alcinse " [Alca, Uria) are all 

 nearly related to each other and to the Penguins. The Gulls, Mews, and Terns {Larus, 

 Gavia, Sterna), and the Albatroses (Diomedea), are all more highly specialized forms 

 than their relatives the Plovers. The most highly modified birds amongst the web- 

 footed tribes, however, are the " Totipalmatse," viz. the Cormorant, Gannet, and Pelican. 

 This small group is of the greatest interest to the student, because, although there 

 are but few genera, yet the relationships of these genera are numerous. The Tropic- 

 bird (Phaeton) is evidently a modified Tern (Sterna) ; the Frigate-bird (Pregata, Ray ; 

 Tachypeles, Vieillot) a near congener of the Petrels ; and the Cormorant is related 

 both to the Grebes on one hand, and to the outlying " Anatinse " (Merganser, Mergus) 

 on the other ; whilst the Booby and Gannet (Sula) are evidently more related to 

 Colymbus, Uria, and Alca. The Anhingas or Darters (Plotus) are, most likely, modifi- 

 cations of the Gannet, and might be thought, by no great stretch of fancy, to be the 

 imagos of the Plesiosaurus. The culmination of the group takes place in the Pelicans, 

 just as the Herons terminate in the Adjutant, the Plovers in the Great Bustard, and the 

 Fowl-tribe in the Turkey. 



I cannot, in this place, eater into the relations of the Bird with the other class-groups ; 

 but the use of the term imago brings to mind that marvellous metamorphosis of the 

 vertebrate form which the anatomist has seen to take place who has passed carefully 

 upwards from the lowest fish to the highest bird. Every embryologist knows that this 

 metamorphosis, which in the Vertebrata can only be fully seen by passing from class to 

 class upwards, is not really greater than that which, in most insects, takes place in the 

 life-history of a single individual. Analogically, the fish is the vertebrate larva, the 

 reptile the more developed but slow pupa, whilst the bird is the lovely imago. 



' Mr. Bartlett informs me that the httle Finfoot of South America is the identical link wanting to connect 

 the Coot with the Grebe. 



