RHODOCRINID&. 255 
Archezocrinus lacunosus (BILiiNGs). 
Plate X. Fig. 1. 
1857. Glyptocrinus lacunosus— Biuines; Geol. Rep. Canada (Rep. of Progr), p. 261, also ibid. 1859, 
Decade IV., p. 61, Plate 8, Figs. 3 a-e. 
1881. <Archeocrinus lacunosus — W. and Sr.; Revision Paleocr., Part I1., p. 190. 
The only known specimen is somewhat crushed, and its exact form can- 
not be ascertained, but it was probably subglobose. The median line of the 
rays is followed by ridges, which grow quite prominent upon the distichals, 
and the surface of the plates is completely covered by small rugose pits and 
wrinkles. 
Infrabasals very minute, not visible from a side view. Basals unusually 
large, the largest plates of the calyx; their truncated upper side very wide. 
Radials slightly smaller than the basals, the two facing the posterior side hep- 
tagonal, the others pentagonal, all sharply angular below. Costals rather 
small. The three lower distichals take part in the calyx; they are small 
and curved like free arm plates. Arms ten at their origin, rounded, rather 
delicate, bifureating once or oftener, the branches divergent, and composed 
of short interlocking pieces. Interbrachials large ; those between the radials, 
which are almost as large as the basals, rise to the middle of the second 
distichals, and are followed by two plates in the second range, and others 
above ; anal side wider, plates arranged: 1, 3, 4, efe. Column round, tap- 
ering considerably downward; the nodal joints very high, even those next 
the calyx, which are twice as wide as the intervening ones, and thick and 
rounded at the edges; the internodal joints comparatively short. At six em. 
from the calyx the internodes contain five joints, and this number apparently 
does not increase in the lower part of the stem. 
Horizon and Locality.— Upper part of Trenton group; Ottawa, Canada. 
Type in the Canada Survey Museum at Ottawa. 
Archeocrinus pyriformis Bririyes. 
Plate X. Figs. 3a, b. 
1857. Thysanocrinus (Rhodocrinus) pyriformis—B. Brurnes; Geol. Rep. Canada (Rep. of Progr.), p. 263 
1859. Rhodocrinus pyriformis —B. Bruures; ibid., Decade IV., p. 61, Plate 6, Figs. le-d. 
1881. <Areheocrinus pyriformis —W. and Sr.; Revision Paleocr., Part IT., p. 190. 
A large species. Calyx obconical or pyriform; one fourth higher than 
wide; greatest width across the second distichals, slightly contracting above. 
