no 
SMITHSONIAN INSTITUTION 
Cremacrinus punctatus Ulrich 
Plate 28, figs. 16-20 
Cremacrinus punctatus Ulrich, 14th Ann. Rep. Geol. Surv. Minnesota, 1886, p. 107, fig. i. 
This species is figured here in order to correct the error in the original 
description due to imperfect material, by which it appeared to have only two 
lateral arms, one on each side. It has the four arms characteristic of the genus, 
one median and three lateral, unsymmetric. The fourth arm, right anterior, 
which owing to injury is missing in the type (fig. i6a), is present in several 
specimens subsequently acquired from the same locality and horizon, as shown 
by figures 17, 18, and 19, but in none of them are all the side arms preserved 
to their full length. So far as can be observed, the fourth arm does not appear 
to be materially smaller than its fellows, which would lead to the inference that 
in this species, derived from an earlier formation than the Canadian species, 
the process of elimination by dwarfing of the fourth arm had not yet begun. 
The median arm is preserved to the end in one specimen, where it consists of 21 bra- 
chials, the last one axillary, and becomes very slender. One ramus of the left posterior arm is 
also intact, showing 7 ramules, with two more added by a terminal bifurcation. The position 
of the stem to the right of the anal tube in the hollow of the right posterior interray is ad- 
mirably shown by figure 17, with the deep indentation resulting from contact when the crown 
was recumbent. Another sirecimen, figure 20a-, gives an excellent picture of the hinge, with 
its denticulate margin and numerous “ supplementary plates.” The cup in this species is 
slightly constricted, widening downwards, height to greatest width as 6 to 6.5 ; primibrachs 2 ; 
brachials in series of 2 and 3. 
Horizon and locality. Black River (Decorah), Ordovician, below the horizon of C. artic- 
ttlosns; Minneapolis, Minnesota. 
Additional species referable to Cremacrinus are Calceocrinus furcillatus and C. rugosus 
of W. R. Billings, and Castocrinus billingsianus Ringueberg, all from the Trenton of Canada. 
