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BATOCRINIDZ&. 369 
Megistocrinus, of which a species may possibly exist in the Mountain Lime- 
stone of England—and are replaced by the Actinocrinidz. This is also 
the case in the western territories of the United States. At Lake Valley, 
New Mexico, among many hundred Camerate Crinoids collected from the 
horizon of the Burlington group, we found only one or two straggling 
Batocrinoids. — A 
The genera for which this family is proposed, with the exception of 
Compsocrinus, have been heretofore referred by us and others to the 
Actinocrinidse, and most of the species were originally described under 
Actinocrinus. Even the genus Batocrinus was not accepted by the earlier 
writers. This was no doubt largely due to the fact that Casseday in 
describing the genus overlooked the arrangement of the plates of the anal 
area, which, as we think, forms the principal distinction between the two 
groups. He only alluded to the meeting of the distichals and palmars over 
the interbrachials, and the separation of the latter from the plates of the 
ventral disk. The importance of the structure of the anal area was pointed 
out by us in the Revision, Part II., p. 159, when we recognized the genus 
Batocrinus, but at that time we only made it the type of a subgroup under 
the Actinocrinide. Ae 
As now defined, the Batocrinide are by far the largest family of the 
Camerata, and they have a greater stratigraphic range than any except 
; the Rhodocrinide, 
Lower Silurian, and continuing into the Warsaw. The family consists of rR 
appearing first in the Hudson River group of the 
eighteen genera, of which twelve, so far as known, are restricted to America, 
and six to Europe; while Periechocrinus and Megistocrinus occur on both 
sides of the Atlantic. Of these genera two hundred and three good species 
have been recognized, — fifty of them coming from Europe and one hundred 
and fifty-three from North America. 
There are in Europe two other genera which probably ought to be 
placed in this family, — Polypeltes Angelin, and Spyridiocrinus Oehlert ; but 
as the arrangement of the two or three proximal rings of plates in the calyx 
cannot be made out in the specimens, they may possibly belong to the 
Melocrinide. 
We have subdivided the genera of this family into two sections, which 
will considerably facilitate identification, viz. :— 
