and on some Gliaracteristics of the Beptilian Birds, 81 



the Reptilian Birds and the first of the Marsupials or hemitypic 

 Mammals (with probably some typical species of each of these 

 classes). Thus the Vertebrate type, commencing at the point ot 

 approximation of Reptiles and Fishes, expanded until each of its 

 higher classes had representative species, before the inferior division 

 of true or typical fishes — Teliosts — came into existence. After- 

 wards, in the Cenozoic, the true or typical Birds and Mammals 

 had their full expansion. 



The Vertebrate type, therefore, not only was not evolved along 

 lines leading up from the lower sub-kingdoms, but ^^^s not, as 

 regards its own species, brought out in lineal order from tlie 

 lowest upward. The sub-kingdom has therefore most evidently 

 a separateness and a roundness below, so to speak, or an entire- 

 ness in its inferior limits, which belongs only to an independent 

 system. 



We find in the facts no support for the Darwinian hypothesis 

 with regard to the origin of the system of life. 



II. The Classification of Animals based on the principle of 

 Cephalization, 



No. I. 



As the principle of cephalization is involved in the very foun- 

 dation of the diverse forms that make up the Animal Kingdom, we 

 may look to it for authoritative guidance with reference to the 

 system that prevails among those forms. Some of its bearings on 

 zoological classification have already been pointed out.* 1 pro- 

 pose to take up the subject more compreliensively ; and, in the 

 present article, to bring the light of the principle to bear on the 

 relations of the Sub-kingdoms, Classes, Orders, and some of the 

 tribes of animal life. 



It is essential, first, that the methods or laws of cephalization 

 be systematically set forth, that they may be conveniently studied 

 and compared. The following statement of them is an extension 

 of what has already been presented : — 



As an animal is a cephalized organism (or one terminating an- 

 teriorly in a head), the anterior and posterior extremities have 

 opposite relations. The subdivision of the structure into anterior 

 and posterior portions has therefore a special importance in this 

 connection. As these terms are used beyond, the anterior por- 

 tion properly includes the head, which is the seat of the senses 

 and mouth, with whatever organs are tributary to its purposes, 



* Expl, Exp. Keport on Crustacea, p. 1412. 1855 ; Amer. Jour, of Science 

 and Arts [2], xxii. 14, 1856; xxxv. 67, xxxvi. 1, 1863. 



NEW SERIES. VOL. XIX. NO. I. JANUARY 1864. L 



