101 



use of this interval, which, as has been observed, has something similar to it in 

 Poteriocriuites and Cyathocrinites, is yet unexplained. I have sometimes con- 

 jectured that it may have included the opening of the oviduct. 



To the upper angles of the scapulae adhere two oblong cuneiform joints, 

 forming as it were a short double arm, having sometimes the point of 

 their inner angle truncated for the admission of a minute square plate. From 

 the superior angle of each of the cuneiform joints proceed (PL. i. fig. 1.) on 

 the sides approaching a series of joints forming the hand, and on the outer sides 

 a finger composed of two slightly horse-shoe shaped joints, on which a double 

 series of joints are arranged, bevelling off and dovetailed at their inner margin 

 into each other, and thus resembling the finger joints ofEncrinites moniliformis. 



Thus the series of joints forming the HAND, (Ft. v. fig. 17. to 36.) proceed 

 each from the inner angle of the two cuneiform arm joints affixed to the 

 scapula: ; they vary in their form, the first joint being simple, convex towards 

 the middle of its outer margin, slightly excavated above, to admit the next or 

 second joint, which by the irregular form of its upper and lower edges resem- 

 bles a double wedge, (fig. 33. to 35.) Above this two half joints are inserted, 

 on which another cuneiform joint rests, sending off two fingers each like the 

 first, formed of a double series of joints. 



The first joints of the hand adhere laterally at their approaching surfaces to 

 each other, and are here somewhat truncated to admit the minute square plates 

 mentioned before ; at their outer lateral surface they adhere firmly to the first 

 joint of the first finger, which again connects laterally with the pectoral plates. 



The FINGERS (PL. v.fig.37. to 51. )are formed of two series of joints, adhering 

 where they dovetail laterally into each other by a muscular integument onl y : this 

 accounts for not unfrequently meeting specimens where their series have sepa- 

 rated in this part for a considerable length, and thereby neatly displayed the 

 interior formation and insertion of the first tentacular joint. 



PECTORAL PLATES. (PL, iv. fig. 27. to 23.) Between the scapulae are inserted 

 several series of small hexagonal, heptagonal, and octagonal plates, connected 

 with the integument covering the abdominal cavity, so often already alluded 

 to in other specimens. These I have named the pectoral plates ; they seem to 

 be capable only of a very slight muscular contraction. 



