69 
finely striated joints; having a contracted circumference of articulation. Its 
column has sometimes numerous joints (fig. 18.) swelling gradually out, and 
thus giving it a barrel-shaped appearance. generally pressed’ in on one of its 
sides, and becoming there concave, with a central perforation evidently leading 
to the alimentary canal. This has all the appearance of acicatrized wound, and 
as the alimentary canal in the column is not increased, the swelling can only 
arise from a more rapid secretion from these joints, probably to strengthen it, 
and to compensate thus for the injury probably sustained in one of its auxiliary 
side arms. The cavity before mentioned, was probably produced by the loss 
or separation of the stump of the injured auxiliary side arm from the column, 
and the subsequent ا‎ azine of the بسن‎ 
The Base of the column is probably Eg to that of tlie genus Cyatho- 
crinites, which will be hereafter described. 
The Pzrvis (fig. 8.)—On the superior columnar: joint rest, as far as I have 
been able to ascertain, five plate-like joints, which I consider, though with 
some hesitation, (for reasons stated in the note, page 67.) as forming the pelvis. 
At their lower surfaces they are smooth, but have a transverse subtriangular 
ridge, with a central perforation and a narrow lip-like extension. Their lateral 
surfaces are slantingly truncated to admit the intervention of a muscle, ል ridge 
divides the upper surface into two angularly slanting planes, having each a 
transverse ridge perforated by a nourishing vessel, aud showing a lip-like pro- 
cess near the inner surface. ‘Phe superior and inferior surface is, near thé ex- 
terior circumference finely striated for the adhesion and transmission of muscu- 
lar portions, connecting with the exterior muscular covering of the crinite; and 
capable of producing on contraction numerous minute tubercles, which may be 
| observed in well preserved specimens. 
The [Bs f pae PLATE-LIKE JoINTS (fig. 6. 7.9. theanimal having rio: 
costals), are oblong and hexagonal, one of them being somewhat longer, and hav- 
ing one of the sides of its superior surface considerably larger. "They insert 
their inferior angle into the five angular spaces formed by the plate-like joints of 
the pelvis, articulating to them by nearly similarly marked surfaces. "They pre- - 
serve externally the subconical figure, and thus enlarge the abdominal cavity. 
The ScAPUL (fig. 2. to 5.) are inserted into each of the superior angles ofthe 
intercostals, They are thin, plate-like, and subpentagonal, adhering by subtrian- 







