488 Scientific Intelligence. 
at the present time, especially in view of the wide interest felt in 
the practical applications of electricity, and the excellence of this 
treatise cannot fail to be appreciated by all who use it. 
2; ’ . G. Tarr, M.A., etc. 368 pp. 8vo. London, 
1884 (Macmillan & Co.).—The well-known name of the author is 
whose design is more strictly scientific, for there is a freshness in 
the method of treatment which makes it valuable and suggestive 
to all. : 
II. GroLtogy AND Narurau Hisrory. 
1. Genera of Fossil Cephalopods ; by Professor A. Hyatt, 
(Proc. Boston Soc. Nat. Hist., xxii, April, 1883). — Professor 
Hyatt gives in this memoir the last results of his extended study 
of the Nautiloid, Ammonoid and other groups of Ce halopods. 
Of these results not the least important are his interesting deduc- 
tions as to the genesis of the group, based on comparisons of the 
successive forms of the whorls in individual shells, and with the 
Successive forms in geological time. He appears thus to prove 
iv 
opment of an individual, and for the different stages in the 
since, to announce the “law of acceleration in develo ment’’ as - 
‘an explanation of quickened or abrupt steps under the theory of 
evolution, which he now prefers to designate the law of “con-_ 
