76 GENERAL ORNITHOLOGY. 
any of which are teleotypic of their ancestorsqgglt may be further observed that any form 
which is teleotypic in its own group, is prototypic of those derived from it. Thus, the 
Archeopteryx, so prototypic of modern birds, was a very highly specialized teleotype of its 
own ancestry. A little reflection will also make it clear that the same principle of antitypes 
(opposed types) is applicable to any of our groups in zodlogy. Any group is teleotypic of the 
next greuter group of which it is a member; prototypic of the next lesser one. Any species is 
teleotypic of its genus; any genus, of its family; any family, of its order; and conversely ; 
that is to say, any species represents one of the ulterior modifications of the plan of its genus. 
The Class of Birds, for example, is one of the several teleotypes of Vertebrata, i. e., of the 
vertebrate plan of structure; representing, as it does, one of several ways in which the 
vertebrate prototype is accomplished. Conversely, the Class of Birds is prototypical of its 
several orders, representing the plan which these orders severally unfold in different ways. 
And so on, throughout any series of animals, backwards and forwards in the process of their 
evolution; any given form being teleotypic of its predecessors, prototypic of its successors. 
All existing forms are necessarily teleotypic, —only prototypic for the future. Prototype, in the 
sense here conveyed, indicates what is often expressed by the word archetype. But the latter, 
as I understand its use by Owen and others, signifies an ideal plan never actually realized; the 
‘« archetype of the vertebrate skeleton,” for example, being something no vertebrate ever pos- 
sessed, but a theoretical model — a generalization from all known skeletons. The correspond- 
ence of my use of ‘‘ prototypic” with a common employ of ‘‘archetypic,” and of ‘‘ teleotypic” as 
including both ‘ attypic” and “ etypic,” is noted below.? 
The actual and visible genetic relationships of living forms being practically restricted to 
individuals of the same species, —parents and offspring “‘ specifically” identical, —it would seem 
at first sight that species must be the modified descendants of their respective genera, in order 
to be teleotypic of any such next higher group. But nothing descends from a genus, or any 
other group; everything descends from individuals ; a ‘‘ genus,” like any other group, is an 
abstract statement of a relation, not a begetter of anything. To illustrate: the ‘ genus 
Turdus” is represented, let us say, by a score of species: if these species be rightly allocated 
in the genus, they are all the modified descendants of a form which was, before they severally 
branched off, a specifie form; and the ‘‘ genus Turdus” in the abstract is simply that form ; 
and that form is prototypic of its derivatives. In the concrete, as represented by its teleotypes, 
the genus Turdus sums the modifications which these have collectively undergone, without. 
specifying the particular modifications of any of them; it expresses the way in which they are 
all like one another, and in which they are all unlike the representatives of any other genus. 
Thus what is above advanced is seen to hold, though genera and all other groups are actual 
descendants of individuals specifically identical. 
Generalized and Specialized Forms. — Taking any one group of animals— say the genus 
Turdus, of numerous species — and considering it apart from any other group, we perceive that 
it represents a certain assemblage of characters peculiar to itself, aside from those more funda- 
mental ones it includes of its family, order, ete. Its particular characters we call ‘ generic.” 
Among the numerous teleotypic forms it includes, there is a wide range of specific variation, 
1 “ Archetypical characters are those which a group derives from its progenitor, and with which it com- 
mences, but which in much modified descendants are lost; such, for example, is the dental formula of the Educa- 
bilia (M 2 PM +0118 x 2), —a formula, as shown by Owen, very prevalent among early members of the group, 
but generally departed from more or less in those of the existing faunas. Attypical characters are those to the 
acquisition of which, as a matter of fact, we find that forms, in their journey to a specialized condition, tend... 
Etypical characters are exceptional ones, and which are exhibited by an eccentric offshoot from the common stock 
of a group.’ —(Gill, Pr. Am. Assoc. Ady. Sci., xx, 1873, p. 293.) To illustrate in birds: A generalized lizard-like 
type of sternum is archetypic of any bird’s sternum. The sternum of the lizard-like animals whence birds 
actually descended is prototypic; the keeled sternum of a carinate bird is attypical in most birds, etypical in the 
peculiar state in which it is found in Stringops; but equally teleotypic in both instances. 
