Pr,ATYCRlNIR.E. — CARIOCRINUS. 65 



The perfect manner in which these variously shaped plates fit against each other is 

 exceedingly interesting, and the varied lines of granules which intersect them in so many 

 directions add greatly to the beauty of the ornamented exterior. 



The second series of plates are eight, all more or less hexagonal ; six of these have 

 each two small plates resting on their upper edges, making twelve in the aggregate ; the 

 remaining two of the second series are prolonged, and arch over between the rays till 

 they meet the abdominal plates on the vertex. All the second series of plates have lines 

 of perforated and smaller granular, which observe the same arrangement as the first in 

 respect to running in the direction of the angles of the plates, and the smaller granules 

 also following their outward contour. 



The second series of plates bend considerably inward, and thus leave a much smaller 

 space on the vertex than is more generally the case with crinoids. 



The Ray-bearing Plates — ten in number, are small and not very regular in shape, 

 they are closely attached to the upper edges of the second series, and appear scarcely 

 larger than the rays themselves. Mr. Say describes the second series of plates as bearing 

 the rays, but we have been enabled to trace the divisions between their upper edges, and 

 the true ray-bearing plates quite distinctly in well-preserved specimens. 



Including the ten ray-bearing plates the third series consists of twelve, two of which 

 are excavated in such a manner as to form the inferior portion of the oral aperture. 



The Abdominal Plates amount to ten or twelve, or even more, six of which, occupy- 

 ing the centre, are larger than the others ; most of them are irregular hexagons, though 

 the two central plates are more frequently heptagonal, and cover the space between the 

 mouth and anus, which latter is a narrow elongated valvate opening situated exactly 

 opposite the oral orifice, and a little within the larger gioup of rays. 



Each plate has from one to five or more tubercles on its surface. 



Mr. Say represents the Cariocrinus ornatus as having but eight " capital plates ;" his 

 specimens must therefore have been badly developed, or he has surely made some 

 mistake in counting them. 



The Mouth is small, and placed a little within the line of the rays. It appears to 

 have been valvate and protrusive, but not proboscidiform. 



The Rays. — The primary rays are ten arranged in three sets, those on either side the 

 mouth consist of three rays each, and the largest group of four is placed on the side 



