OF ARTS AND SCIENCES. 29 



rate our genus from Dichocrimis. When these interesting animals 

 have been further investigated, it is probable that a better classification 

 may be introduced. 



ALLOPROSALLOCRINUS, Nov. Gen. 



Generic formula : — 



Basal pieces, . . 3. • 



Radial pieces, . 2x5. 



Secondary radial pieces, 2x5. 



Anal pieces, . . 3 to 4, or more. 



Inter-radials, . . 1x4. 



Arms, . . . 11 to 13 ; variable, form unkown. 



Column, small (?) ; form unknown. 



Vault covered with numerous polygonal pieces. 



Mouth proboscidiform. 



Alloprosallocrinus conicus, Sp. Nov. 



Body conical ; calyx plane or slightly saucer-shaped, columnar pit 

 excavate, involving the basals and part of the pieces which close the 

 circle around them. 



Basal pieces three, two of which are much larger than the third, 

 irregularly pentagonal. 



Radial pieces. The first radials, five in number, are large, hexago- 

 nal, differing considerably in size ; three rise upon the summit of the 

 basal pieces, and two rest in the notches between them. The second 

 radial pieces are pentagonal, axillary, differing in size and form, each 

 of the two upper oblique margins supporting one of the secondary 

 radial pieces ; these, ten in number, vary in size and form ; triangular, 

 quadrangular, and pentangular pieces being all found in a single indi- 

 vidual. These in turn support another series of pieces of the second- 

 ary radials, larger than the other pieces of the ray, twice as broad as 

 high, subquadrangular, thick, indented by a deep sinus upon the upper 

 margin. One of the postero-lateral rays, and sometimes both, have an 

 additional secondary radial, in which case it is similar to the first 

 secondary radials. 



Arms. The arms vary in number ; the regular rays support each 

 two arms, and the postero-lateral ray to the left of the anal field 

 supports three ; making eleven arms. Sometimes both postero-lateral 



