154 ECHINODERMATA—PELMATOZOA SUB-KINGDOM III 
them twice as large as the other, and the two forming a knob-like body. L 
five, their inner edges resting upon the angular margin “of the basal disk : they 
spread broadly aabeard from the 5 extending Te beyond them. The two 
larger 2 separated at the posterior side by two equal smaller met: and at 
ia anterior side by a single plate having a quite narrow upper face. J/. 
holetus, Schultze, apparently with fice arms; their structure anion 
Middle Devonian ; Eifel. 
Family 6. Calceocrinidae. Meek and Worthen. 
“Tnadunata Monocyclica, in which a bilateral symmetry along the left anterior 
radius and right posterior interradius has been superinduced in conjunction with 
bending of the crown on the stem in such a way that the right posterior interray lies 
along the stem; with the left anterior, right posterior, and right anterior radials com- 
pound , with anal « (IRA) shifted over the right posterior radius, usually into the 
right posterior interradius, and supporting a massive tube; with three, rarely four 
arms, of which two are as a rule peculiarly modified and bear armlets or pinnules.” — 
Lather, The Crinoidea of Gotland. Ordovician to Sub-Carboniferous. 
Castocrinus, Ringueberg. B distinct, all entering into the articular surface 
of the stem. The right posterior, and right antero-lateral superradials 
joined by ill-defined close suture, each abutting with one side on the 
adjacent large simple I’. The lower plate of the tube supported by the 
right posterior superradial only, while the right antero-lateral superradial 
supports the first brachial of the right antero-lateral arm. The right posterior 
and right antero-lateral superradials separated from one another, and also 
from the ventral tube, by the right posterior and right antero-lateral 2. Arms 
four. Ordovician; North America. Type, C. furcillatus, W. R. Billings sp. 
Euchirocrinus, M. and W.  B unfused, or perhaps sometimes the left pos- 
terior fused with the left antero-lateral one. The right posterior and right 
antero-lateral superradials fused in a T-shaped piece, which abuts with either 
wing on the corners of the large simple 2. The right posterior and right 
antero-lateral inferradials separated from one another and from the tube 
by the T-piece; tube supported by the whole upper margin of the latter. 
Arms three. Ordovician and Silurian; North America. Type, 2. punctatus, 
Ulrich sp. 
Caleeocrinus (Hall) Ringueberg. Left posterior B fused with the left 
antero-lateral one; the fused plates very rarely entering the stem articula- 
tion. The posterior and right antero-lateral B bounded for some distance by 
the large f. T-plate separated from the large simple & by the right 
posterior and right antero-lateral R, it is low, wide, and occasionally very 
small. Tube supported by the T-piece and the two inferradials to the right, 
but not touching the two large simple radials. Arms three. Silurian and 
Devonian ; Europe and America. Type, C. typus, Ringueberg. 
Halysiocrinus (Ulrich) Bather. £2 as in the preceding, but the fused 
posterior and right antero-lateral ones never entering into the stem articula- 
tion. ‘T-piece either obsolete or concealed between the right posterior and 
right antero-lateral inferradials, and the two large 7? in the stem articulation. 
Tube supported by the inferradials to the right, which are in contact ; and 
abutting by its lower corners on the two large simple 2. Arms three. Bur- 
lington and Keokuk Groups ; Mississippi Valley. Type, //. ventricosus, Hall sp. 
