Description oj Four JSfew Sj^ecies, etc. 235 



the Hudson River Group at CincinDnti, at an elevation of about 140 

 feet above low- water mark. It is the onl}^ one that I have seen. Some- 

 times I have thought that it is abnormal and might be L. craterifor- 

 mis.hwt as there are more plates in the head of it than belong to that 

 species, and as the head is thrown into elevations and depressions, 

 that are not the result of disturbance occasioned by any rough surface 

 to which it may have attached (it is now attached to the plane surface 

 of a palmate coral), and as the column is so distinct, I have ventured 

 to propose for it a distinct specific name. The peculiar characters of 

 the head are not verj- well shown in the engraving. 



I suppose that all species in this genus were free in their habits, and 

 floated with the head downward, but attached to clay stones, shells 

 and corals b}" the entire lower surface of the head whenever so-dis- 

 posed. The column was free and used to direct and guide the course 

 of the animal through the water, and perform such other functions as 

 were performed by the columns of other floating crinoids, except that 

 it was never used for purposes of attachment. The animals were 

 gregarious in their habits, for we not unfrequently find a dozen or more 

 attached to a single claystone, and sometimes the}'' encroached upon 

 each other and piled more or less one upon another. It is probable 

 that they" remained attached to some foreign body the greater part of 

 the time, but the manner in which they are sometimes found, piled 

 upon each other, shows, not that they grew in that wa}^, but that thc}^ 

 floated and attached in that manner, b}' accident. In some cases, it 

 appears as if one specimen had first attached itself to a clay stone, and 

 afterward another in attempting to attach itself to the same object, 

 extended itself over upon -the body of the one first attaching when the 

 latter withdrew the i'>art so covered. This appearance of contracting 

 and withdrawing part of the bodj' is not of unfrequent occurrence. The 

 head was evidentlj' ver}^ flexible and capable of a wide expansion over 

 a smooth surface, but always covering much less space when the sur- 

 face to which it attached was rough or irregular. 



Dendrocrinus navigiolum, n. sp. 



Plate VII., lig. ^K, spe^imcQ, natural size; fig. Xa, the same magnified. ^• 



This is a small delicate species. The head is obpj'ramidal. It is 

 distinctly pentagonal at the junction with the column, and sub-pen 

 t agonal above. 



The basal plates are pentagonal, longer than wide, and together 

 form the distinctly pentagonal base of the bod\'. Subradials hexag- 

 onal, larger than the basal s, and much longer than wide. First radials 

 shorter and wider than the subradials, and having a general heptag- 



