JTofi's OH ('(t iiihr'nl II KiliiiKlx. 3ftlffjii'ii\ :>s 1 
should ttike this view, as one of the first chapterst (k4ails ilhis- 
trative experiments to give the reader the first conception of re- 
current expansion. 
The fact is. that tiiere 1^ no limit to the latei-al movement pro- 
vided 1)V recurrent expansion, excepting the natural limit of the 
numl)er and intensity of the successive changes of temperature. 
I can assure Prof. Hutton that if T had advanced no further 
than the single constructive conception of cuhical expansion as 
an agent in Mountain- Building, in itself original — or. at all 
events, not containe<l in the Herschel. Hal)l)age, Scrope. or JiVell 
conceptions of the effects of expansion on the earth's crust — the 
'•Origin of Mountain-llanges would never have l»een written. 
CONCLI'SION. 
The ohject of this outline l)eing to correct some prevalent mis- 
conceptions of my views. I have confined myself principally to 
restating in a shorter form the essential principles of my theory 
of mountain-formation by sedimentaiy loading and cumulative 
recurrent expansion. For all the details, proofs, illustrations. 
and numerical calculations I must, as before stated, refer those 
interested to the original work. Perhaps it may lead some who 
have already read the -Origin of Mountain-Ranges" to again read 
and reconsider it. when 1 trust the points 1 have touched on in 
this outline will a(hl to its lucidity. Honest criticism, even if 
severe, is one means of elucidating the truth, and T not only 
invite Ijut welcome it. 
Park Corner, Blundellsaiids. 
Liverpool. 
NOTES ON CAMBRIAN FAUNAS. 
\\\ •■■ V. Maithkw . St. -lulin, >••« l>rini-w iiU. 
1. Till T<li<iinr Ftmiiii iif Kiiuiloii.f cniii.p'i r>i/ irifli ( 'ii hi li ii<i ii 
/lori'.oiis 'if tlir St. -foil II (Iruiip. 
in view r»f the discussions now going on or that have been held. 
in regard to the vi'xed (piestions of Taconic and ( 'ambrian. a fj'w 
words of comment on this hjiig imperf\'ctly-understood and little 
known fauna, may not be considen'd out of i)lace from one who 
has been at work on the lower paheozoic locks (')f a neiglilior- 
ing region. 
Emmons' original types have at length been fully elucidaletl. 
*Ihi<L Chap. III. 
