CALYPTOCRINID. 331 
Fic. 14. Fic. 16. 
Fie. 14, showing plates of the dorsal cup, the arms and their partitions. 
Fig. 15, the calyx in a side view. 
Fie. 16, the partition walls of Eucalyptocrinus rosaceus (after Schultze). 
b=hbasals; R= Radials; 7=costals; 77=distichals; ir = interbrachials ; 7d = interdistichals 
A=arms; irP = interradial partitions; idP = interdistichal partitions; (2 = first ring of plates of the 
tegmen; /2—the second ring; /3=the third ring; and ¢4=the fourth or upper ring of the tegmen. 
plates limited to a certain number. The dorsal cup is perfectly pentamerous, 
the rays being separated by interbrachials of uniform number and size, and 
their main divisions by a single large interdistichal. Still more important 
from a classificatory point of view is the structure of the ventral disk, which 
differs from that of any other known Crinoid, recent or fossil. Jt is com- 
posed of only four rings of large plates of irregular form, of which the two 
lower ones completely cover the disk ambulacra, which are subtegminal, the 
upper ones forming a long neck or tube enclosing a narrow canal. Not 
only do the plates of the disk, like those of the dorsal cup, consist of a defi- 
nite number, but they are throughout this family unusually large, and their 
arrangement does not appear to be in accordance with the pentamerous 
