AKT. 3. TERTIARY CRINOID FROM WEST INDIES SPRINGER. 3 



columnals, of which the upper one, with tlie radial structures much 

 injured by corrosion, may be a nodal, but no facets are visible (figs. 

 4, 4a) . In this specimen it is seen how the radial ridges have been 

 partly decomposed, leaving the petal floors between them promi- 

 nently preserved. This condition is further shown in Figure 6a, 

 where the ridges are destroyed and the resulting pentamerism is 

 emphasized. In Figures 4, 5, and 6 the eifect of weathering and 

 decomposition upon the sides of the stem is shown, producing more 

 or less longitudinal projections, in some rounded and in some 

 angular. Figures 2 and 3 show the distortion of the columnals by 

 crushing. 



All the stem-fragments in their normal condition, that is, when 

 unaffected by weathering, crushing, or chemical action, are strictly 

 cylindrical in outline. The slightly quinquelobate aspect on some 

 of the joint faces is due to peripheral abrasion along the weaker 

 radial lines at the edge of the sectors. The stems range from 6 to 

 9 mm. in diameter, with about 8 mm. preponderating. The side 

 faces are invariably smooth except where injured, as shown in several 

 figures. 



Returning, now, to the cirrus-facets, we are fortunate in having 

 one specimen in which they are very plainly shown upon the syzy- 

 gial face of one of the nodal segments, which I suppose to be the 

 epizygal (figs. 9, 9a). They are three in number, two at adjacent 

 radii and the third directly opposite these two, leaving the space at 

 the intervening radii blank. They stand obliquely to the syzygial 

 face, projecting somewhat from its general level, and their position 

 is marked by obtuse ridges diminishing inward and engaging with 

 corresponding depressions in the apposed face of the contiguous 

 nodal segment. In another specimen, not figured, similar facets of 

 the same number and position are faintly indicated. The two facets 

 shown in Figure 8, with a third one opposite to them obscurely seen 

 but not visible in the figure, are similarly disposed. Therefore 

 upon the concurrent evidence of three specimens it may be fairly 

 assumed that the normal number of cirri in this species is three to 

 a nodal, distributed according to the definite plan described by Doctor 

 Bather in his paper of 1917 (p. 396) as " not (all) adjacent, but one 

 is opposed to the two others, being separated from them on each 

 side by a blank radius . . . svmbolized thus : 



A b C D e." 



He shows how the cirrus-facets alternate upon successive nodals, 

 and the same thing probably happens here, there being, as already 

 stated, some evidence of such an alternation in the facets on the 

 terminal nodals in Figure 8. The cirrus-facets are extremely small 

 compared with the size of the stem, not over half the height of the 

 nodal pair, thus resembling those of the Eocene species, B. suh- 



