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4. Radials separated at the posterior side by an anal plate. 
First anal plate heptagonal, followed by a second between inter- 
DACIMMAUIS, cop0 neo Doan 0900000000 00000000000000 90000000 BATOCRINID 
First anal plate hexagonal, followed by two interbrachials without 
a second anal; arms branching from two main trunks by alternate 
[ONABTREAIUOM «g000560600000000000000 0000 000 00600000000 ACTINOCRINID& 
Il. BRACHIALS AND INTERBRACHIALS ONLY SLIGHTLY REPRESENTED IN THE 
DORSAL CUP. 
1. Dicyclic. 
Radials in contact except at the posterior side.......... CROTAOCRINID A 
2. Monocyclic. 
a. Radials in contact all around; base pentagonal....... PLATYCRINID 
6. Radials separated on posterior side by ananal plate; base hex- 
agonal. Basals directly followed by the radials........... HEXACRINID & 
Basals separated from radials by accessory pieces.......... ACROCRINID& 
While the morphological and classificatory chapters of the mono- 
graph on North American crinoids appeal more directly to palzontolo- 
gists interested in the biological side of the subject, the descriptive part 
will be of greatest practical value to the stratigraphical geologist. ‘This 
portion of the work is a complete revision of all Camerata known from 
this country up to September 1894. Every species is fully and clearly des- 
cribed compared with closely related forms, beautifully illustrated and 
referred to its proper geological horizon; the full literature of each and 
the localities where it occurs are also given. All the species have been 
redescribed from the most perfect material that could be found in all 
museums and private collections. The liberality shown Wachsmuth and 
Springer by those persons who possessed suitable specimens in placing 
them at free disposal is to be commended in the highest terms. It was 
the means of making accessible nearly all the type specimens known, 
and in fact, most of the crinoid material in the country. In addition 
there were the authors’ own magnificent collections which contain more 
than nine-tenths of the known American species and over two-thirds of 
the European, of which many are represented by scores and even hun- 
dreds of individuals. These large collections gave new ideas regarding 
the limits of the different species and enabled a discrimination to be 
made between species and varieties, and between the young specimens 
and the adults, which led to the elimination of a large number pre- 
viously recognized. The establishment of species on rational morpho- 
logical grounds and not on trivial superficial or accidental characters 
which are relatively unimportant as classificatory criteria is a point of 
excellence which cannot be too highly praised, and one which should 
