MELOCRINIDAE 
25 
Family MELOCRINIDAE Zittel 
Of this extensive monocyclic family, with the radials in contact all around, 
the collections here in hand contain eight genera, two of them foreigners now 
first recognized in this country, one which though known before has developed 
an unexpected wealth of species, and one new. 
MACROSTYLOCRINUS 
Plate 4 
Maci'ostylocrinus Hall, Pal. New York, 2, 1852, p. 203. — Wachsmuth and Springer, Rev. Pal., 2, 1881, 
pp. 96, 102; N. A. Crin. Cam., 1897, p. 285. — Bather, Treatise on Zool., 3, 1900, p. 162. — Zittel- 
Eastman, Textb. Pal., 2d ed., 1913, p. 191. — Jaekel, Phylogenie und System, 1918, p. 36. — Bassler, 
Bibliogr. Index, Bull. 92, U. S. Nat. Mus., 1915, p. 782. 
BB 3 unequal; anal interradius wider than the others above level of RR; 
arms lO, simple, biserial. 
Genotype. M'cerostylocrinus ornatns Hall. 
Distribution. Silurian and Devonian ; America, England. 
This typically Silurian genus, but now known to occur in the Lower Devonian,’- which 
has hitherto been accounted as one of the rare fossils, is well represented in the present collec- 
tions, especially for illustrating the structure of the tegmen, heretofore unknown. Several 
species are figured, all but one previously described, and of these it is not deemed necessary 
to repeat the descriptions. 
Macrostylocrinus fasciatus Hall 
Plate 4, figs, g, ga, b 
Macrostylocrinus fasciatus Hall, 28th Rep. New York St. Mus., 1879, p. 130, pi. 13, figs. 5, 6. — Wachsmuth 
and Springer, N. A. Crin. Cam., 1897, p. 288, pi. 22, fig. 13. — Bassler, Bibliogr. Index, 1915, p. 782. 
The specimen here figured has the fasciculated striae, rarely well preserved, 
perfectly distinct, and shows correctly the full dimensions of the calyx and the 
form and proportions of all the plates. The important feature, however, is that 
it has the tegmen intact, which has not been found before. Usually the upper 
part is broken away, so that the great elongation of the cup does not appear. 
The tegmen is composed of a great number of small smooth plates, traversed 
from the center to arm-bases by narrow, almost linear, ambulacra. The small 
anal opening lies at the extreme margin, where it projects between the two 
posterior rays, connecting with the median row of anal plates on the dorsal side. 
Radial series sharply defined by a median ridge. Total height of calyx 13 mm. 
Horizon and locality. Waldron shale, Niagaran ; Hartsville, Indiana. 
1 Springer, Unusual Forms of Fossil Crinoids, Proc. U. S. Nat. Mus., Vol. 67, 1926, p. 33. 
