HETEROCRINIDAE 
123 
the distal part of the median arm. Two calices are also figured of the same or a closely allied 
species from equivalent horizon in other areas. 
Horizon and locality. Hamilton group, Middle Devonian ; Alpena, Michigan, New 
Buffalo, Iowa, and Clark County, Indiana. 
Halysiocrinus perplexus (Shumard) 
Plate so, figs. 4-13 
Cheirocrinus (Calceocrinus?) pcrplcxns Shumard, Trans. St. Louis Acad. Sci., 1866, 2, p. 358. 
Some specimens of this species are figured in connection with the explana- 
tion of the hinge already given, for which it offers unusual facilities. It occurs 
in the New Providence shale of the basal Lower Carboniferous,^ and is found 
chiefly on weathered exposures at Button Mould and other knobs south of 
Louisville in Kentucky. Complete crowns are unknown, but the two charac- 
teristic elements of the united radial plates and separate consolidated basals have 
been collected by hundreds, among which are many that furnish a clear expo- 
sition of the structure of these parts. They vary in size from cups lo mm. high 
by 6 mm. wide at the top and 8 mm. at the hinge line, to those 20 mm. high, 
which increase in width from 14 mm. at the top to 33 mm. at the hinge — thus 
showing* a tendency to become wider basalward with age. Some differences may 
be noted among the specimens which might indicate the presence of more than 
one species, such as the greater or less projection of the superradial, and varia- 
tion in surface from pustulose to smooth; but the latter is largely a matter of 
erosion, and in default of more complete material I have referred them all to 
the original species. 
Horizon and locality. New Providence shale, Mississippian ; Button Mould Knob, and 
other localities widely distributed in Kentucky and Tennessee, and Clark County, Indiana. 
Halysiocrinus dactylus (Plall) 
Plate so, figs, i, 2 , 2 a, b, 3, Set 
Cheirocrinus dactylus Hall, 13th Rep. New York St. Cab. Nat. Hist, i860, p. 123, figs, i, 2. — Halysiocrinus 
dactylus Ulrich, 14th Ann. Rep. Geol. Stirv. Minnesota, 1886, p. no. — Cheirocrinus ventricosus Hall, 
13th Rep., supra, p. 123. — Halysiocrinus ventricosus Bather, Crin. Goth, pp. 65, 66, pi. 4, figs. 141, 142. 
I am illustrating this Lower Carboniferous species because it has been 
designated as the type of the genus, and for the further reason that doubt has 
been expressed as to its standing, some authors thinking it may be a synon3^m 
of Hall’s C. ventricosus from the same formation — both having been described 
in the same publication. I am therefore figuring the type specimen in the 
Museum of Comparative Zoology, together with some others from my own 
collection showing further details. The type, also well figured by Hall, gives 
a complete picture of the generic characters, whereas C. ventricosus was de- 
1 Knobstone of authors, and by some erroneously referred to the Keokuk. See Springer, The Crinoid 
Fauna of the Knobstone formation. Proc. U. S. Nat. Mus., Vol. 41, 1911, p. 178. 
