386 The American Geologist. Jone ae, 
trilobitic genera noted, but at least half a dozen others among 
which may be mentioned Conocephalus, Bathyurus, and Ag- 
raulus. Altogether between 70 and 75 species that were iden- 
tifiable were found by members of the Missouri Geological 
Survey before the few fragmentary specimens mentioned by 
Beecher came into his hands. 
in regard to the little brachiopod, Lingulella lamborni 
Meck, as a determiming factor of the geological age of the 
rocks of southeastern Missouri, it may be said that it was 
distinctly recognized that its value was mi/. In fact, it at no 
time ertered into consideration. Winslow’s statements*, re- 
garding the age of the Magnesian limestones, it is believed, 
were based upon notes taken several years previous, before 
fossils had been found abundantly in the rocks in question. 
My own statementst quoted by Beecher, that in the Mine la 
Motte district “no strata younger than Cambrian are be- 
lieved to be represented,” and that “but few fossils have been 
found in the rocks of the area, so that the fossil evidence as 
to the geological age is somewhat meager” manifestly apply 
only to the small area upon which the special report was 
made—an area in the granite region, 13 by 17 miles. The 
statements are clearly not general observations on the whole 
of the state. As recently quoted a very erroneous ‘impres- 
sion is given. 
In this connection, it may be mentioned that soon after 
the publication of the report last alluded to, Mr. Greger, of 
the Missouri survey also collected in south Missouri a large 
numbe of Cambrian forms, in addition to those species previ- 
ously cbtained. His account and descriptions of species were 
to have been printed more than two years ago. 
The Cambrian age of the Magnesian limestones of south- 
east \lissouri was also inferred from data derived from two 
other independent methods of correlation. Carefully made 
geological cross-sections clearly showed that most of these for- 
mations lay beneath the base of Lower Silurian or Ordovician 
rocks. As to geological age, everything down to the bottom 
of the Trenton limestone had long been definitely deter- 
mined * Moreover, exact comparisons regarding the lith- 
* U.S. Geol. Sur., Bull, 132, p. 11, 1896. +..0, sos a 
+ Missouri Geol. Sur., vol. ix, pt. iv. p. 44, 1895. 
~ Missouri Geol. Sur., vol. viii, p. 99, 1896. 
ge ec ke of 
