NO. 1850. KNOBSTOXE CRINOID FAUNA— SPRINGER. 189 



ACTINOCRINUS Miller. 



A. jugosus Hall, or a similar species, occur at Wliites Creek, but 

 not found in place. The base and loose plates of the same type were 

 found at the Joe Bell Knob, near Ivebanon, Kentucky, associated 

 with Dorijcrinus gouldi, and probably came from the upper limestone. 

 There are also a few loose plates at Button-mould Knob referable to 

 some species of Actinocrinus. The genus ranges from the Lower 

 Burlington to the Keokuk. 



CACTOCRINUS Wachsmvxth and Springer. 



Arm fragments characteristic of this genus, with short, spmy nodes 

 on every third, fourth, and fifth brachial, were found at the Knobs. 

 No trace of this genus has been seen above the Lower Burlmgton. 



Localities. — Button-mould Knob; Stone's Farm; Whites Creek; 

 Fern Glen. 



PLATYCRINUS Miller. 



Many detached radial plates, and a few basal disks. All are of 

 Lower Burlington types, and not one of them can be positivel}'^ referred 

 to a Keokuk species or type. Several forms can be distinguished 

 which may be compared with described species as identical or closely 

 alhed. My comparison is mainly with species knowTi at BurUngton, 

 and not with those described by Miller from the Choteau of Missouri, 

 some of which are probably closer, but of which I have not the speci- 

 mens at hand. 



1. Discoid form, base only; small, thick, with very coarse nodes, 

 elongated toward the corners of the basal pentagon: cf. P. yandelli 

 Owen and Shumard, Lower Burlington. 



Locality. — Button-mould Knob; Bradbury Knob, Kentucky. 



2. Low discoid form, base only; very small with a single prominent 

 node just below each corner of basal pentagon: May be P. ameri- 

 canus Hall, or young of P. yandelli, both Lower BurUngton. 



Locality. — Button-mould Knob. 



3. Discoid form with very long radials, and facets projectmg 

 beyond the limits of the calyx, proximal part of the rays very deep 

 and narrow. It is the form described by S. A. Miller from the Lower 

 Burlington at Sedalia, Missouri, as P. occidentalis ,^ which is a good 

 species of this type, and not a s3aionym, as stated in North American 

 Crinoidea Camerata, page 728. 



Locality. — Wliites Creek, in place in the gray limestone; it occurs 

 also at Fern Glen, and a form jjrobably identical with it is abundant 

 in the equivalent beds at Lake Valley, New Mexico. 



The discoid Platycrini are characteristically Lower Burhngton, and 

 not Keokuk. 



'Bull. No. 4, Geol. Surv. Missouri, p 10. 



