Miss Agnes Crane — Evolution oflhe Bracliiopoda. 103 



for other questions, sucli as that of the migrations of the Lower 

 Cretaceous faunas, a time scale which is independent of lithological 

 characters is equally necessary. These two scales are not contra- 

 dictory, but complementary, and each must be retained for its special 

 purposes — the one for local purposes and the other for a universal 



time scale. Thus they correspond in history to the methods of dating 

 events bj' dynasties or by centuries. If this be understood there 

 need be no confusion lietween them, though the statement that part 

 of the Lower Greensand is Gault, sounds like saying that this weeic 

 is part of last week. But we can say without such paradox, that 

 part of the Lower Greensand is of Albian age, though that stage 

 is in England typically represented by the Gault. 



IL — The Evolution of thk Brachiopoda. 



By Agnes Crane. 

 (PLATE V.) 

 [Continued from the February Number, p. 

 Part II. 



75.) 



IT is evident that neither Barrande nor Davidson, w^ho maintained 

 the opinions I have summarized till the last in their publications, 

 were able to recognize the evidence deducible from a study of the 

 Brachiopoda favourable to the theory of their evolution. 



The solution of tlie problem was left for a contemporary worker 

 in the same field of inquiry, and for the younger school of American 

 brachiopodists versed in all the modern methods of embryological 



