46 



This species is so different from all others that no comparison 

 witli any of tlifMu is necessary to (listiu<:;uisli it. 



Found by Prof. A. G. Wetherby, in whoso honor we have pro- 

 posed the specific nam?, in the Kaskaskia Group, in Pulaski 

 county, Kentucky, and now in the collection of \Vm. F. E. Gur- 

 ley. 



Family POTERIOCRINIDiE. 



POTEBIOCRINUS VAGULUS, n. sp. 



PUde 4, Fly. 10, (izijgous side on ihe Jcfl ; Fi;/. J], opposiie view 



of stinic specimen. 



Species medium size, robust, arms coarse, calyx obconoidal, 

 truncated below, about as long as wide; sutures distinct; surface 

 granular. Column large, tapering from the calyx, and composed 

 of moderately thick plates. Columnar canal small. 



Basals rather large, longer than wide and forming an obpyra- 

 midal cup. Superior angles obtuse. Sul)radia]s rather longer 

 than wide, four hexagonal, one heptagonal. First radials wider 

 than long and truncated the entire width al)ove. Second radials 

 shorter than the first and truncated tlie entire width above, at 

 which point the five arms seem to have become free without the 

 usual gaping sutures or other special {)rovigious for a free move- 

 ment. Above the second radials the arms continue without any 

 apparent decrease in diameter to the first and probably the only 

 bifurcation. This takes place on the eighth plate in the arm on 

 the left of the azygous area, on the sixth plate in one of the lateral 

 arms and in the arm opposite the azygous area the eighth plate is 

 cuneiform, not axillary, and beyond this it is not preserved in our 

 specimen. The other two arms are not preserved in our specimen 

 as high as the place of bifurcation. Probably, the arm opposite 

 the azygous area remains single and the two arms not preserved 

 divide as in the first two above described. Two of the arms are 

 preserved as high as the twelfth plate above the first bifurcation 

 without any evidence of another division. It, therefore, appears 

 that only four aims divide and tliat this species possesses five 

 arms in the lower part and nine in tiie upper part. The arms 

 are composed of thort, cuneiform plates, and are round externally, 

 showing three-fourths of the circumferance, which necessarily 

 leaves the arm furrows very narrow. 



