xvi THE HISTORY OF ZOOLOGY 651 



no clear idea of genera, his genera being rather what we now 

 call orders or families, and he showed an undue conservatism in 

 retaining, as far as possible, the groups of Aristotle. His general 

 classification of animals is as follows : 



I. Animals with (red) blood [Vertebrata]. 



1. Respiration pulmonary. 



A. Heart with two ventricles. 



(a) Viviparous. 



i. Aquatic (Cetacea]. 

 ii. Terrestrial [other Mammalia]. 



(b) Oviparous [Birds]. 



B. Heart with one ventricle. 



Viviparous Quadrupeds and Serpents [i.e., Reptilia 

 and Amphibia]. 



2. Respiration branchial [Fishes]. 



II. Animals without (red) blood [Inverlebrata]. 



1. Majora. 



A. Mollia [Cephalopoda]. 



B. Crustacea. 



C. Testacea [Gastropoda and Pelecypoda], 



2. Minora. 



Insecta [Insecta, Arachnida, Myriapoda, and Vermes]. 



It will be noticed that, while the classification of Vertebrates is 

 fairly natural, being founded upon the rock of anatomy, the arrange- 

 ment of Invertebrates is no advance upon that of Aristotle : the 

 two main divisions depend upon mere size ; and Crustacea, 

 separated from the rest of the Arthropoda, are interposed between 

 Cephalopods and the remaining Mollusca. In association with 

 Ray must be mentioned his friend and fellow-worker Francis 

 Willughby, who made extensive contributions to Zoology. 



The eighteenth century saw the imperfect efforts of Ray developed, 

 and in some respects perfected, by Carl Linne, or Linnaeus, 

 universally recognised as the founder of modern systematic 

 Zoology or more accurately Biology, since his reforms equally 

 affected Botany. Born in Sweden in 1707, two years after Ray's 

 death, he published the first edition of his Sy sterna Naturce, in 

 1735, as a small pamphlet. The twelfth edition (1766-68) was in 

 three volumes, and was the last to receive the author's corrections, 

 but from materials left at his death in 1778 an authoritative 

 (thirteenth) edition in ten volumes was prepared by J. F. Gmelin. 



It was Linneeus who first recognised the value of groups higher 

 than species genera, orders, classes, &c., and employed them 

 in a definite and uniform way, with due subordination of one to 

 the other ; it was he who invented binomial nomenclature, the 

 advantage of which in promoting precision in systematic work 



