508 SIMUEDIOES. JRO SI(QLOIBIN IGS 
have nowhere a uniform succession of rocks, and nowhere an 
unbroken genetic series. It has been shown how often the facies 
of the Pacific coast? region has changed, and how it now belonged 
to one faunal region, and now to another, each great change in 
faunal geography showing some physiographic revolution here 
or elsewhere. Thus the local series is broken and filled in from 
other regions, species being classed together because of resem- 
blance, while their real relationship is unknown. 
LAW OF ACCELERATION OF DEVELOPMENT. 
Since the geologic record is so badly broken, and since mod- 
ern faunas and floras are but the topmost branches of a tree 
whose stock is only partly known, naturalists were merely grop- 
ing in the dark in their efforts to get a genetic classification. 
There was however a glimmer of light, although scarcely heeded. 
No one man seems to have been the discoverer of the law of 
acceleration of development, but like the idea of evolution, it 
was in the air, and disclosed itself in various ways to the pro- 
phetic vision of seekers after truth. J. F. Meckel,? a German 
naturalist, seems to have been the first to give scientific expres- 
sion to the biogenetic law, in his formula, ‘‘Gleichung zwischen 
der Entwicklung des Embryo und der Thierreihe,” comparison of 
development of the embryo with the race of animals. But Louis 
Agassiz, although not the discoverer, was undoubtedly the first 
to use the law as an aid in the systematic study of biology. 
While he regarded the various genera, not as ancestors and 
descendants, but as progressive steps in creation, still he saw the 
analogy between the stages of growth of the individual and these 
progressive steps. It was reserved for Alpheus Hyatt to formu- 
late the law, and to strengthen theory with practical examples 
based on study of Cephalopoda.’ In his later papers Professor 
t Jour. GEOL., Vol. III, May-June 1895, Mesozoic Changes in the Faunal Geog- 
raphy of California. J. P. SMITH. 
2 Syst. Vergl. Anat., I., Theil Halle, 1821. 
3A. Hyatt, Mem. Boston Soc. Nat. Hist., Vol. I, 1866-7, and Proc. Boston Soc. 
Nat. Hist., Vol. I, 1866, “‘ Parallelisms of Individual and Order among the Tetrabran- 
chiate Moliusks.” 
