52 



DOLATOCRINUS HAMMELLI, 11. sp. 



Plate V, Fir/. 4, basal view, the rim nroiind the cavitij is a little 

 out of shape i)i the specimen, and is subpentagonal in- 

 stead of hexacjonal; Fig. 5, side vieio; Fig. 6, 

 stimmit view of the same specimen. 



Species medium size. The specimen illustrated is the smallest 

 of six before us, but the largest is not moi-e than one-fourth more 

 in diameter. Calyx low, basin-shaped, specially expanded at the 

 arms, from three and a half to four and a half times as wide as 

 high, deeply and broadly concave below, the depression extending 

 to the third radials. Columnar pit funnel-shaped, and bounded 

 externally by a pentagonal, raised ridge running from a tubercle 

 in the middle of the superior part of each first radial plate to the 

 next adjoining. Eadial ridges merely sharp elevations crossing 

 the plates and interrupted by shai'p nodes at the center of each 

 plate. Surface radiately sculptui-ed. Column round, inserted into 

 the cup formed by the basal plates, and having a cinque. Foil 

 columnar canal. 



Basal plates form a round cup so deeply inserted in the calyx 

 that it rises, in some specimens, higher than the calyx, and ends 

 in the cavity of the vault. The mouth of the cup is one-third 

 wider than the diameter of the column. First primary radials as 

 wide as high, smooth below the pentagonal rim and tubercles 

 from which the radial ridges arise, slightly sculptured above. 

 Second primary redials twice as wide as high, slightly expanding 

 above and quadrangular. Third primary radials expanding up- 

 ward to the lateral angles, longer than the second, pentagonal, 

 and supporting, in one ray upon each upper sloping side, a single 

 secondary radial, which is axillary, and supports upon each upper 

 sloping side two tertiary radials, which gives to this ray four 

 arms. In each of the other four rays the third primary radial 

 bears upon one upper sloping side three secondary radials, and 

 upon the other a single secondary radial, which is axillary and 

 bears upon each upper sloping side two tertiary radials, which 

 gives to each of these rays three arms. There are, therefore, six- 

 teen arms and sixteen ambulacral openings to the vault in this 

 species. 



The fir t regular interradials are elongated, nine-sided plates, 

 peculiarly sculptured, by having one deep longitudinal furrow in 

 the upper part. They are followed in the second range by a sin- 



