CRAP TODISCUS, HAHL 807 
showed Cryptodiscus to be but a portion of the dome of mem- 
bers of that genus. 
Figure 9, Plate B, isa diagram adapted from Wachsmuth and 
Springer, to show the arrangement of the plates in the calyx of 
Callicrinus costatus His., the type of the genus. The dome is 
composed of four ranges of plates, of which the first contains 
ten, and the second, third, and fourth ranges, four plates each. 
Figure 8, Plate B, shows diagramatically the arrangement of 
the plates in the Racine specimen. The three ranges of plates 
present in these specimens correspond to the second, third, and 
fourth ranges in the dome of C. costatus. The plates in the 
Racine specimens differ from those of C. costatus in the third 
range; the two lower plates of this range are not in contact lat- 
erally, as in that species, but are separated by the downward 
extension of the two upper plates, which meet the truncated 
upper ends of the two corresponding plates of the second range. 
The most conspicuous difference between the Racine specimens 
and C. costatus, is in the greatly expanded margins of the plates 
of the fourth range, forming the disk to which the name Cryféo- 
discus has been applied. 
Figure 5, Plate A, which shows the external impression of a 
portion of a disk attached to the tube, is introduced to show 
a peculiar ring-like canal which surrounds the tube just below 
its junction with the disk. This canal is open entirely around 
the tube so far as it is preserved, and a pliable wire inserted at 
one side passes around and out on the opposite side. On the 
impression itself, just above the angle between the disk and the 
tube, is a series of small slit-like openings which apparently 
connect with the ring canal. In the actual specimens, of course, 
these openings were represented by a solid ring around the tube, 
which was supported by a series of small bars connected with 
the basal portion of the under side of the disk. No explanation 
of these characters can be offered. 
In their monograph, ‘“‘The North American Crinoidea Cam- 
erata,’’ Wachsmuth and Springer recognize from the dorsal cups 
alone, four species of Cadlicrinus—C. beachleri from St. Paul, 
