STUDIES IN ANIMAL LIFE. 95 



etc.), Acephala (oysters, etc.), Brachiopoda, and Oir- 

 rhopoda (barnacles). — ^N.B. This last class is now 

 removed from the Mollusks and placed among the 

 Crustaceans. 



The Aeticulata are composed of four classes : 

 Annelids (worms), Crustacea (lobsters, crabs, etc.), 

 Arachnida (spiders), and Insecta. 



The Eadiata embrace all the remaining forms ; 

 but this group has been so altered since Cuvier's 

 time that I will not burden your memory just now 

 with an enumeration of the details. 



The reader is now in a condition to appreciate 

 the general line of argument adopted in the discus- 

 sion of Mr. Darwin's book, which is at present ex- 

 citing very great attention, and which will, at any 

 rate, aid in general culture by opening to many 

 minds new tracts of thought. The benefit in this 

 direction is, however, considerably lessened by the 

 extreme vagueness which is commonly attached to 

 the word " species," as well as by the great want of 

 philosophic culture which impoverishes the major- 

 ity of our naturalists. I have heard or read few 

 arguments on this subject which have not impress- 

 ed me with the sense that the disputants really at- 

 tached no distinct ideas to many of the phrases they 

 were uttering. Yet it is obvious that we must first 

 settle what are the facts grouped together and indi- 

 cated by the word " species," before we can carry 

 on any discussion as to the origin of species. To 

 be battling about the fixity or variability of species, 



