FOSSILS OF THE BUBLINGTON GROUP. 435 



iiildaucf. however. to Tajcocrinux. it is evident that this group is 

 more nearly allied to Cyathocrinw. If it has, as seems to be the case, 

 five basal pieces, the formula of the genus would be as follows : 



Basal piecrs ". subradials 5, all of the same form ; radials 4 to 5 x 5, 

 the first being large and forming the larger part of the body, the others 

 small and free; anals 0; interradials 0; arms bifurcating, and resem- 

 bling those of Tajcocrinux. 



Some five or six specimens of this type show that the absence of anal 

 pieces is not an abnormal, but a constant character. 



XiPTEROCRixrs WACHSMITHI. ~M. and W. 



PI. 2. fig. 4. 

 \tpttrocrimu Waetitmuthi, MEEK and WORTHKX. Proceed. Acad. Xat. ScL, Phila.. 1868, p. 341. 



BODY rather deeply basin-shaped, or a little more than 

 twice as wide as high, rounding under from the top of the 

 first radials to the column. Base small, flat, and nearly 

 hidden by the column. Subradial pieces of moderate si/e. 

 somewhat wider than long, and all pentagonal, there being 

 no visible angle at the middle of the under side of any of 

 them. First radials comparatively very large, or about 

 three times the size of the subradials, twice as wide as 

 high, and all alike pentagonal, while each is provided with 

 a rather deep, rounded sinus above, equaling about one- 

 third of its breadth, for the reception of the succeeding 

 radials, on each side of which its upper margin is nearly 

 straight, horizontal, and not incurved. Second radials so 

 short as scarcely to till the sinus in the upper side of the 

 first, and owing to the concave outline above, often pre- 

 senting a narrow, transversely crescentic form. Third and 

 and fourth radials (where there are five) very short, or sev- 

 eral times as wide as long, and usually somewhat arcuate 

 inversely. Last (fourth or fifth) radial a little longer than the 

 next below, and generally trigonal or subpentagonal (the 

 upper angle being somewhat salient), and supporting the 

 arms on its sloping sides. Arms rounded, rather divergent, 

 and bifurcating on the sixth or seventh piece above their 



