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CLASSIFICATIONS OF THE MAMMALIA. 
Rodentia. Rodents : Hares, rabbits, &c. 
Cheiroptera. Bats. 
Insectivora. Moles, hedgehogs, &c. 
Cetacea . Whales, dolphins, &c. 
Sirenia . Dugongs, &c. 
Edentata. Sloths, anteaters, &c. 
Marsupialia ... Opossums, &c. 
Monotremata ,. The Ornithorhynchus and Echidna. 
In this arrangement physiology and anatomy have been 
largely aided by the modern sciences of palaeontology, the 
study of extinct and fossil forms ; embryology, the examina¬ 
tion of the young in their progressive stages ; and histology, 
the microscopic investigation of tissues. Yet it is still but 
an instantaneous photograph of Nature as she appears at a 
given moment, and makes no attempt to represent the stream 
of Mammalian life in its entirety. 
About the beginning of this century a curious system was 
propounded by Mr. Macleay, and adopted by the naturalist 
iSwainson. It was called the quinary system, the idea being 
that organic nature consisted of a network of circular groups, 
related to each other by affinities and analogies in a very 
complicated manner. There is a certain attractive truth in 
this idea, but the system based upon it was too rigidly 
mathematical for Nature’s work, and could not live in the 
broadening light of science. Swainson and his followers 
maintained that the organic world was dominated by the 
number 5. That the ideal genus had 5 species, the ideal 
family 5 genera, the ideal order 5 families, and the ideal 
class 5 orders. To the class Mammalia they assigned the 
five following orders, and attempted to show their symbolical 
relationship with the 5 orders of Birds, and in the same 
manner with the Reptiles, Fishes, &c :— 
MAMMALIA. BIRDS. 
Ferae . Carnivorous . Raptores. 
Primates. Omnivorous . Insessores. 
Glires. Frugivorous . Rasores. 
Ungulata. Moisture-loving. Grallatores. 
Cetacea. Aquatic. Natatores. 
Swainson’s works were published fifty years ago, and are 
now little known or read, but they are full of suggestive 
thought and well worth referring to. 
If ever we are to break away from the instantaneous 
photograph method, if ever we are to take a broader view 
of classification, to get a more comprehensive grasp of Nature 
as a whole, it must bo by tracing the lines of blood 
