FOSSILS— THEIR NATURE AND INTERPRETATION. 93 



earlier and appeared in the Ordovician era, but ceased with 

 the Paleozoic time, and its subordinal characters — viz., the six 

 primary septa — date back as far as the Cambrian era, and are 

 being repeated in the generation of species living at the pres- 

 ent time. Thus, in the case of an individual specimen of 

 Favosites niagarensis, we can point to one character and say, 

 This character continued to reappear in other individuals until 

 the close of the Niagara era, then it ceased; of another, This 

 character continued to reappear until the close of the Paleo- 

 zoic time; and of a third character. It is still appearing in 

 individual organisms now living in the ocean. The facts in 

 the case may be graphically expressed by the following table : 



TABLE EXPRESSING THE GEOLOGICAL RANGE OF THE CHARACTERS 



OF THE FOSSIL FAP-OSITES NIAGARENSIS (HALL), ARRANGED 



ACCORDING TO THEIR TAXONOMIC RANK. 



Specific characters 



Time- values of the Characters of an Individual Differ according 

 to their Taxonomic Rank. — We learn from this analysis that any 

 particular fossil represents a particular living animal, whose 

 time of living was identical with that of the formation of 

 the rock in which it was buried; also that the fossil ex- 

 hibits morphological characters of various taxonomic rank, 

 and these characters have a time-range quite of the .same 

 order as their taxonomic rank. In any particular organism, 

 fossil or living, the characters of highest rank in classification 

 are historically the oldest, and the characters of lowest taxo- 



