DIMEROCRINIDAE 
19 
couple of others that may perhaps go with it. The chief difference ol)servable 
is that here the base is less deeply excavate, and the BB, instead of being raised 
into a stellate ridge, are sharply nodose, forming a well defined pentagon. 
Horizon and locality. Beech River formation, Niagaran ; from the glades in Decatur 
County, Tennessee. 
Gazacrinus stellatus new species 
Plate 2, figs. 2g a-c 
This species is the only instance in which the genus has been recognized 
from beyond the limits of the Silurian. The unique specimen upon which it is 
based comes from the Linden formation of the Helderbergian, the lower beds 
of which in some Tennessee localities lie in very close relation to the Decatur 
limestone at the top of the Niagaran, where it almost seems as if there is an 
intermingling of typical fossils. The species, while in general similar in size and 
proportions to G. ramifer, is clearly distinct in detail. The basal cavity is sharply 
defined, the edge forming an acutely pointed pentagon with straight sides. The 
BB and other calyx plates are covered with coarse pustules, which tend to 
coalesce below into lines forming raised triangles on the radials, but with more 
isolated rugose markings on the other plates. 
Horizon and locality. Linden formation, Helderbergian, Lower Devonian; Hardin 
County, Tennessee. 
Two species have been described by Weller from the Racine dolomite of the Chicago 
area, and one by Hall from the Rochester shale at Lockport as Thysanocrinus has been re- 
ferred to the genus. For list and synonymy, see Bassler, Bibliogr. Index, 1915, p. 545. 
LAMPTEROCRINUS Roemer 
Plate y 
Lampterocrinus Roemer, Sil. Fauna Westl. Tennessee, i860, p. 40. — Wachsmuth and Springer, Rev. Pal. 2, 
1881, pp. 184, 199; 3, 188s, p. loi ; N. A. Crin. Cam., 1897, p. 207. — Bather, Treatise on Zool., 3, 1900, 
p. 199, fig. 124. — Zittel-Eastman, Textb. Pal., 2d ed., 1913, p. 187. — Jaekel, Phylogenie und System, 
1918, p. 41. For further references see Bassler, Bibliogr. Index, 1915, p. 689. 
Calyx subturbinate, similar to that of Dimerocrimis but asymmetrical owing 
to bulging at anal side; iBr few, anal interradius wider than the others; rays 
produced into 5 tubular extensions, bearing uniserial, pinnuliferous arms at 
each side, with more than one pinnule to a brachial; tegmen composed of 
numerous convex plates passing into a strong, subcentral tube ; column sharply 
pentagonal. 
Genotype. Lampterocrinus Tennesseensis Roemer. 
Distribution. Silurian ; America. 
In the Revision of the Palaeocrinoidea, pt. 2, p. 200, and in N. A. Crinoidea Camerata, 
p. 207, Wachsmuth and Springer described the brachial arrangement of this genus as con- 
sisting of lateral appendages, in which the brachials, from primibrachs up, roofed by covering 
pieces were extended into single rigid tubes, or free rays, giving off the arms laterally. This 
