NO. 1850. KNOBSTONE CRiNOID FAtJ^\4.—8PRiKGER. ^03 



short, with small, deep, and narrow crescentic facets, having a trans- 

 verse ridge. IBB of this species not found, but calyx above them 

 reconstructed from plates wliich are fairly plentiful at the Knobs, 

 but not observed at Whites Creek. It is of the same type as Hall's 

 ^' Cyathocrinus" macro pleurus,^ which has been erroneously referred 

 to Vasocrinus. It is a rare species from the Lower Burhngtonat 

 Burlington, scarcely ever found except as detached plates; it also 

 occurs at Lake Valley, New Mexico. It is hard to say how these 

 plates can be distinguished from those of P. crassus, of the European 

 Lower Carboniferous. The same type runs through the Upper 

 Burhngton — P. doris — into the Keokuk, where it culminates in a 

 very large new species, which I expect shortly to describe. 



2. Elongate calyx, with perfectly smooth surface, no ridges or fur- 

 rows, and veiy thin plates; represented by the infrabasal circlet at- 

 tached to proximal column joints, and a few loose basal and radial 

 plates, all from the Knobs. Not known at Burhngton, but indis- 

 tinguishable in the parts preserved from specimens of P. spissus 

 from Tournai, Belgium. 



3. A very large, low, broadly spreading form, with stronger plates 

 than the preceding; smooth surface, and obscure connecting ridges. 

 RR veiy wide and larger than BB ; facets wide and shallow, with dis- 

 tinct transverse ridge. IBB unknown, and characters taken from 

 isolated basal and radial plates, found at Button-mould Knob. The 

 general aspect is more that of Barycrinus; but the very distinct 

 transverse ridge and relatively thin plates seem rather to indicate 

 this genus. Not known at Burlington or elsewhere. 



SCAPHIOCRINUS Hall. 



There is a fine new species of this genus represented by several 

 calices from Wliites Creek, and a nearly complete specimen with 

 arms from some locality in Lincohi County, Kentucky, not far from 

 Junction City. The horizon of either might be Knobstone or Keo- 

 kuk, and at neither is it positively known. There is an undescribed 

 species somewhat similar to it in the Upper Burlington, and another 

 in the true Keokuk at Indian Creek, Indiana. 



There are also some loose smooth plates from Button-mould Knob 

 and Stone's farm wliich can not be distinguished from similar plates 

 from Tournai, Belgium. 



ZEACRINUS Hall. 



Z. nodosus Wachsmuth and Springer." This singular crinoid, 

 having the base of true Zeacrinus and the arms of Scaphiocrinus, was 

 found by Wachsmuth at Wliites Creek in a ravine washed out of 



1 Journ. Bost. Soc. Nat. Hist., vol. 7, 1860, p. 295. " Rev. Pal., vol. 3, p. 243, pi. 6, fig. 9; pi. 9, fig. 3. 



