26o The American Geologist. October, looi. 
"For those are Lower Silurian types, — among the earliest known 
crinoids ; and it is quite possible to suppose, if the crinoids diverged 
into two lines of development on this character, that they represent 
stages somewhat near the point of such divergence. If the two forms 
of base represented in Uintacrinus had been found in specimens other- 
wise separable they would, under Mr. Bather's arrangement, have been 
unquestionably referred to different genera, families, orders, and sub- 
classes. Considering the apparent identity of these forms in every other 
point of structure, coupled with their mode of occurrence and associa- 
tion, I do not see how any such separation can possibly be made in this 
case. We therefore have apparently to deal with a case of individual 
variation, as to this supposed primitive character, within the limits 
of a species. That is to say, in this species, living in the same locality, 
having the same environment, floating in the same mass, certain indi- 
viduals matured to represent one stage of larval development. /. c. with 
infrabasals ; and others in another stage, i. c. with basals only. 
"In short, there are the two supposed distinct types, Monocyclica 
and Dicyclica, occurring in both young and adult of one and the same 
species. It will not do to say that the species is dicyclic, but in a cer- 
tain individuals the infrabasals are not developed, or hidden by the 
centrale, or have disappeared by atrophy. If this were so the centrale 
ought to be interradial in both cases ; whereas, as already shown, its 
orientation is reversed from one to the other, precisely as in typical 
monocyclic and dicyclic forms. 
"At all events, we have in Uintacrinus perfect proof that in some 
cases the characters of a monocyclic or dicyclic base are subordinate 
to others, and do not mark the line of descent." 
The nine beautiful plates of figures give the best graphic represen- 
tation of Uintacrinus that has ever appeared. c. r. k. 
Coal Fields arotmd Tsc Cliou, China; by Noah Fields Drake. (Trans. 
American Inst. Min. Eng., Vol. XXX, pp. 261-277, igoi.) 
On account of the recent exciting changes on the checker-board of 
the far east, the coal supplies of China have an unusual interest. Every 
addition to our knowledge of these coal fields since the explorations of 
Baron von Richthoien, over three decades ago, is now scanned with 
avidity. Dr. Drake's contribution comes at an opportune time. 
The coal fields of Shansi lie about four hundred miles southwest of 
Peking, near the great Yellow river. The long journey was taken 
mainly on slow river-boats, and the somewdiat limited time at the com- 
mand of the author, allowed only work to be done in the district around 
Tse Chou. Until very recently the hostile attitude of the Chinese gov- 
ernment and people towards foreigners and their enterprises, has kept 
the coal-fields from being developed. 
The rock formations are roughly divided into three great terranes. 
There is a basal limestone formation, the Kohlcnkalk of Richthofen, 
aggregating 2,000 feet or more in thickness ; a median formation com- 
posed of shales, coals, sandstones, and a flint-bearing limestone bed, 
