106 PALEONTOLOGY OF NEW- YORK. 



row of ientacula along the fingers. Tentacula round, jointed ; articula- 

 tions nearly twice as long as broad : each articulation, from near its 

 centre on the inner side, giving origin to a secondary round jointed 

 tentacle, producing in this manner a first and second series of tentacles. 

 Interbrachial plates seven or eight or more below the base of the 

 proboscis, on each of the four regular sides. 

 Column round, consisting of joints of nearly equal thickness, becoming 

 thinner towards the body. Canal small. 



This magnificent species of crlnoid differs from several smaller forms of the genus 

 in the smoother plates, which show some remains of obtuse radiating ridges towards 

 their margins in some of the higher plates of the body; while the lower plates are 

 essentially smooth, or with no ornament beyond the fine granulose surface. The 

 structure of the brachial portion is remarkable in presenting an auxiliary arm on 

 each side of the base of the principal arm, and which proceed from the lower bra- 

 chial plates, and have essentially an origin independent of the central arm. 



A remarkable featiu-e of this and other species of the genus is that the main arms 

 give origin to armlets (or fingers, in the nomenclature of Miller), which bear the 

 tentacula; while the joints of the main arms do not appear to bear tentacula, as far 

 as can be observed. 



In all the individuals of this species which have been seen, the extremities of the 

 arms are broken off, and the entire length and expansion are not known. In one 

 specimen, thirty armlets can be distinctly counted on each side; and from the size 

 of the arm where broken off, it is probable that five or six, or perhaps ten more, 

 may have existed. 



The proboscis is only partially shown in a single specimen : its full length is 

 unknown. The column in the small fragment attached to the specimen, Plate ii, is 

 composed of thin joints; while the fragment lying on the specimen, Plate ii a, and 

 other fragments of coliunns supposed to belong to this species, are composed of 

 thicker joints. Judging both from the numerous fragments of columns found with 

 this species, and from the known length of the column in another species, this 

 crinoid was doubtless furnished with a long and strong column. 



PLATE n. 

 Fig. 1. An individual nearly entire, showing a few joints of the column, the plates of the 



body, the arms and appendages. 

 Fig. 2. Enlargement of a portion of one of the arms and armlets. 



Fig. 3 & 4. Enlargement of a portion of one of the armlets, and of one of the first series 

 of tentacula, showing the character and arrangement of the second tentacula. 



