Acervularia Profiinda and Davidsoni.— Calvin. 355 
shows remarkable uniformity of the general conditions over a 
great area, for the total thicknese varies little in the southern 
ecounties of Pennsylvania and for a long distance southward in 
West Virginia; while the more important beds are as persistent as 
similarly important beds in the Lower Coal Measures, at the same 
time the thickness of intervals and the character of the rocks 
filling them show changes more abrupt and more striking than can 
be observed in any other portion of the column. 
The details respecting the Lower Coal Measures and the Con- 
glomerate Measures are of the utmost interest; some of the iden- 
tifications in West Virginia are startling, but there seems to be no 
ground whatever, for taking exception to their accuracy. Nearly 
all of the material respecting West Virginia is new. 
But it is impossible within the limits of a notice to give a 
synopsis of a memoir, which is itself synoptical, a series of pre- 
sentations rather than a series of discussions; so that those in- 
terested in the bituminous area must be referred to the memoir 
itself. Those who have much to do with economic work will find 
this a more than useful handbook to expedite their explorations; 
those who have made careful studies in detached portions of the 
area will feel grateful for the systematic joining of those portions, 
even though it be done at the sacrifice of some cherished conjec- 
tures. Prof. White’s treatment of his colleagues in this field is 
sufficiently comforting; he has ignored our faults and has ob- 
served our virtues—more than once to the extent of labeling good 
work of his own with the name of another, 
HoOPesON THE DIFFERENCES BETWEEN, ACER- 
VULARIA PROFUNDA HALL, AND ACERVU- 
LARIA DAVIDSONI EDWARDS AND HAIME. 
By 8. Carvin, Iowa City. 
The original description of Acervularia profunda Hall is found 
in Hall’s Report on the Geological Survey of Iowa, published in 
1858. The specimens on which the species was 1ounded came 
from near Independence in Buchanan county, Iowa. In the same 
report professor Hall, not without some hesitation, identifies an- 
other form found abundantly throughout the Devonian area in 
Iowa, with Acervularia davidsoni Edwards and Haime, This, so 
far as I have been able to ascertain, was the first time the name 
