202 PROCEEDINGS OF THE NATIONAL MVSEVM. vol. 41. 



Aside from the ornament it has some general resemblance to B. 

 hnllatus of the Keokuk. 



Locality. — Separate brachials with the bead-like fringe of nodes are 

 found at the Knobs, and complete calices at Wliites Creek. 



7. A large, low, wide-spreading species, with finely wrinkled, 

 granulose surface ornament in a variety of forms ; the surface of the 

 plates bent into broad, low ridges branching from RR, meeting on BB, 

 and passing down to IBB, with a slight median groove, leaving 10 

 shallow, lozenge-shaped depressions at the corners where three plates 

 meet. This is the general form and structure of B. waclismutlii of the 

 Lower Burlington, and B. sculptilis of the Upper; but it has relatively 

 thinner plates than those species. The surface sculpturing is delicate, 

 and not suggestive of any of the large Keokuk species. 



Locality. — Plates of this are common at Button-mould and Brad- 

 bury Knobs, Kentucky, and at Stone's and Palmer's farms, Indiana, 

 from which calices have been reconstructed; also at Whites Creek. 

 There is also a large, coarse form, with heavy plates, at the latter 

 locality, probably referable to one of the smooth Keokuk species. 



8. Large, low, spreading calyx, with very convex radials and 

 strongl}'' tumid basals, without any connecting ridges, and with per- 

 fectly smooth surface; it is a good example of B. huUatus Hall, of 

 the Iowa Keokuk. 



Locality. — Whites Creek, from slope with mixed fossils, below level 

 of Knobstone. 



While, as in CyatJiocrinus, several of these species are not decisive 

 of horizon, two of them are of distinctly Lower Burlington type, and 

 there are few among the others which might not belong to that for- 

 mation ; so the weight of evidence, upon this genus alone, is in favor 

 of that horizon rather than Keokuk. 



POTERIOCRINUS Miller. 



The true Poteriocrinus, which includes only a few out of the vast 

 number of species described under this name, is represented by at 

 least two species. The genus, beginniiig in the Devonian, is a strong 

 fossil of the Mountain Limestone of England and Belgium, and in 

 tliis country ranges from the Lower Burlington to the Keokuk. 



1. Large, elongate, with very thin plates which are flexed into 

 deep folds, leaving broad, elevated bands composed of several more 

 or less sharp ridges, passing from the radial facets to one another and 

 to the basals, converging at the middle and passing down to the in- 

 frabasals; a pair of such striated bands passes right and left from one 

 basal to another, with fine granulose ornament between. These 

 marldngs are very conspicuous, and the plates become as thin as 

 paper at the sutures. BB elongate, much larger than RR, which are 



