RHODOCRINIDAE 
23 
form, two of them connecting with the IBB. Arm openings 4 to the ray, directed horizontally 
from a projecting rim ; the r. post, ray bifurcates on the first IBr, but by way of compensation 
this is followed by more than two IIBr ; the arms not preserved. 
All this points to an abnormal specimen, or sport — but of what? The form and general 
structure of the calyx are positive and well defined, and in all the collections from St. Paul 
and the Tennessee localities nothing has been found with which it can be compared. Therefore 
it will have to stand upon the aljove description until the normal form is shown by further 
discovery. 
Horizon and locality. Laurel limestone, Niagaran ; St. Paul, Indiana. 
Wilsonicrinus discoideus new g-eniis and species 
Plate 4, figs. 6, 6a 
This is another Rhodocrinid straggler from the St. Paul beds, known only 
by the single type specimen, and apparently without close relatives. The calyx 
is a broad, wheel-shaped disk, with smooth plates, slightly convex below and 
contracting above to a large snbcentral anal tube. It has 4 IBB sunken into 
a small indented cavity, BB fairly ecjual in size, truncate above and connecting 
with single large iBr. Arm-openings 10, small and widely separated, issuing 
from a series of cuneate IIBr, 
The outstanding feature of this genus is the fixed pinnules originating upon the longer 
face of the IIBr to the number of 4, 5 or 6 on each side in the form of more or less irregular 
pinnulars, which by contact with the IIBr and with each other are incorporated in the cup ; 
they lead directly to interbrachial openings for free pinnules independent of the arms, emerg- 
ing at the margin of the tegmen between the rays and their subdivisions. These are very con- 
spicuous, corresponding in number to the incorporated pinnules. Thus the interbrachial areas, 
above and beyond the single large iBr plates which abut upon the truncated BB, are occupied 
by these fixed pinnules, which have every appearance of higher iBr. For a full discussion of 
the fixed pinnules in various genera and the interpretation of their openings at the margin 
of the tegmen, see my papers on Scyphocriniis^ and Dolatocrinns.^ 
The type specimen was found by my former assistant, the late Dr. Herrick E. Wilson, 
who recognized its highly distinctive characters, and the generic name is proposed in his 
memory. 
Horizon and locality. Laurel limestone, Niagaran ; St. Paul, Indiana. 
Emperocrinus indianensis IMiller and Gurley 
Plate 4, figs. 7, ya 
Emperocrinus indianensis Miller and Gurley. Bull. 6, Illinois St. Mus., 1895, p. 43, pi. 4, figs. 16, 17. — 
Bather, Treatise on Zool., 3, 1900, p. 202. — Bassler, Bibliogr. Index, 1915, p. 476. 
Another rare form, of simpler construction than the preceding, which I 
am illustrating from a new specimen. Instead of being discoid, the calyx is 
pentagonal, and the iBr areas, instead of being filled to the margin with the 
incorporated pinnules, are depressed, contracted and limited to the single large 
1 Smithsonian Publication No. 2440, 1917, pp. 33-37, 40-46; pi. 9, figs. 5-6. 
2 Bull. 115, U. S. Nat. Mus., 1921, pp. 24, 25, pi. 7, figs. 2-5. 
