Prof. J. D. Dana on the Classification of Mammals. 213 



The classification indicated is then as follows : — 



I. Archontia (vel Dipoda) — Man (alone). 



II. Megasthena. 



1. Quadrumana. 



2. Carnivora. 



3. Herbivora. 



4. Mutilata. 



III. MiCROSTHENA. 



1. Cheiroptera. 



2. Insectivora. 



3. Rodentia. 



4. Bruta (Edentata). 



IV. OoTICOIDEA. 



1. Marsupialia. 



2. Monotremata. 



It is interesting to observe, also, that the four orders of Mega- 

 sthenes rise in grade, from the 4th to the 1st, on the principles of 

 cephalization stated ; and this affords other evidence, superadded 

 to that of higher importance based on difference in type of 

 structure, as to the naturalness of these subdivisions. The spe- 

 cies of the 4th (the Mutilates) are characterized by a degrada- 

 tion and partial obsolescence of the limbs, by the body being 

 massively prolonged behind, by a large part of the elongated 

 vertebral column being used for locomotion, by the form and 

 the low grade of structure of the head, and by the teeth, always 

 of extreme simplicity of form, in most species of one set only, in 

 some excessively multiplied in number, in others all wanting — 

 peculiarities indicating a very low degree of cephalization, and 

 even a degradation of the anterior as well as posterior extremity. 

 Those of the 3rd (the Herbivores) by a more abbreviated body, 

 by the two pairs of limbs being complete, but serving only for 

 locomotion, by an elongated head. Those of the 2nd (the 

 Carnivores) by the limbs being still more perfect, and serving, 

 the anterior especially, for grasping, by the head being shorter 

 and more compacted and, in general, more complete in the series 

 of teeth. Those of the 1st (the Quadrumanes) by the anterior 

 limbs serving still more perfectly as hands, by the cephalic 

 extremity being further shortened, also by the mammae being 

 pectoral, as in Man. There is, in the series of orders, an advance 

 by stages towards that acme of cephalization, Man. 



Among the Microsthenes, the rise in rank on this principle is 

 no less apparent. It is well seen between the lowest (the Brutes) 

 and the others. These have posteriorly a remarkably lax verte- 

 bral column, but two or three of the vertebrae being soldered 

 together to form the sacrum. The cephalic extremity exhibits, not 

 only alow grade of cephalic concentration, as shown in the larger 

 number of cervical vertebrae in some species, the excessive num- 

 ber of teeth in some species, the characters of the skull, but 

 also a marked example of cephaUc degradation in the jaws, in 



