24 PROCEEDINGS OF THE AMERICAN ACADEMY 



Dimensions : — 



Greatest diameter of the basis .... 



Least « « u ... 



Height of the first radials ..... 



Greatest width of radials .... 



Height of specimen ...... 



Greatest diameter ...... 



Least diameter ....... 



Geological Position and Locality. This elegant little crinoid is 

 quite abundant near the top of the cavernous beds of the subcar- 

 boniferous limestone, Edmondson County, near the Mammoth Cave. 

 Good specimens are rare. The vertical range of this species, so far 

 as ascertained, is about thirty-eight feet. 



Remarhs. D. elegans is nearly allied to D. symmetricus and several 

 undetermined species ; it will readily be distinguished from D. symme- 

 tricus by its more erect figure, the absence of the strong spinous 

 central piece at the summit, by the greater prominence of the arms, 

 as well as the larger number at the body, and the consequent greater 

 number of small pieces making up the clusters about the arm facets. 



DiCHOCRINUS FICUS, Sp. NoV. 



Body. Subovoid, inflated near the centre of the length of the first 

 I'adial pieces, from which it contracts toward the summit of the calyx ; 

 contracting regularly toward the column, around which it is inflated. 

 Columnar pit small, slightly depressed. 



Basal pieces two, similar in form and size, obscurely pentagonal ; 

 dividing line straight; the summit of the pieces united present five 

 slightly curved depressions, and one angular notch for the reception 

 of the radial and anal pieces. 



Radial pieces, Jirst series five, similar in form and size, a little 

 higher than wide, subquadrangular ; the upper margin slightly in- 

 dented near the middle for the reception of the radials of the second 

 series. Radial pieces, second series, five, minute, semicircular, buried 

 in the indentation at the summit of the first radials. Radial pieces, 

 third series, small, depressed, cuneiform, axillary ; the oblique upper 

 margins of each support two arms. 



Anal piece, — one, similar in form and size to the first radial pieces ; 

 like them it bears a second and third radial, and a pair of arms. 



