Address before the Association of American Geologists. 259 
this family ; but the weight of opinion seems to be on the other 
side. Hitherto I believe, in this country, these relics have been 
found only in primitive regions ; but as it is not always the case 
in Kurope, (Am. Journal of Science, Vol. xt, p. 177,) we may 
believe it is not so here. Over the primary regions they have 
been found from Maine to Wisconsin, and south to Virginia. So 
humerous are the localities, that in New England at deast, am 
confident they may be found in nearly every town based on pri- 
mary rocks. ‘The report on the geology of Massachusetts is en- 
riched with a valuable paper on the fogsil infusoria of that state, 
by Prof. Bailey ; and a memoir on the same subject, embracing 
the whole of the United States. may soon be expected from that 
gentleman. It will give some idea of the wide field which the 
microscope: has opened to palzontology in this country, to state, 
that in a single a panittvent of fossil farina from West Point, Ehren- 
has detected fe f siliceous infusoria. Besides, 
it can hardly be doubted that, our iron ores and other eee in 
“ae to the mcaneteis will afford these remains. 
Pome 
interesting 
te by Prof. W.B. Rogers, in the cdugunee Virginii 
as announced in his Geological Report of 1841, of a. E setiotei of 
these infusoria. It is composed almost entirely of their ir siliceous 
shields, occupies areas of considerable extent, attains 
the enormous thickness of twenty five feet, and is rarely less 
than twelve feet thick. If such is the beginning, pee 
tlemen, will be the end of this infinitestmal geology! — 
seem fast advancing towards a realization of the proverb, inate 
calx e vermibus, omnis silex e vermibus, omne ferrum e vermibus. 
- Having thus ascended to the top of the scale of Ameri¢an 
rocks, ‘and briefly shown how far their characters have been 
fixed, and their equivalence to European strata demonstrated, : ‘al 
few miscellaneous topics only remain for examination, ~~ 
--One of. these subjects is that of concretions. And it petniete 
nie that it needs to have light thrown upon it as much as any in 
the whole range of mineralogy and geology. It needs a second 
Haiiy to develop the fundamental principles of coneretionary 
structure. - Brongniart, De la Beche, and Fitton; have, indeed, 
thrown out many valuable hints on the subject, and rendered it 
probable that -coneretions result from segregation by means of 
elective affinity. But why the particles should arrange them- 
