DESCRIPTIONS OF SOAIE NEW CRINOIDS. 99 



Dome hemispherical, grooved between the arm bases, and composed 

 of numerous small polygonal pieces, which are interposed among a 

 certain number of much larger and more regular plates. The smaller 

 pieces are at their surface slightly convex, and have a somewhat corru- 

 gated appearance; the others are armed each with a strong, short spine. 



Central dome-plate nodose or spiniferous; in close contact with the 

 proboscis. It is surrounded by a circle of irregular pieces, comprising 

 several rows. Outside of these pieces there are interradially six larger, 

 very prominent, spiniferous plates, and around these, somewhat closer 

 to the arms, along the median part of each ray, there is another circlet 

 of ecjually large plates, and also equally spiniferous, which have no 

 connection with the six former ones nor among one another. 



Some of the plates in the calyx have a conspicuous central node; 

 the largest one is on the second radical; there is none on the first nor 

 on the basals, but on all plates radial and interradial to the third radi- 

 cals inclusive, sometimes extending until lost on the succeeding smaller 

 plates. 



Column stout, round, composed of thicker and thinner joints; canal 

 very large, almost circular. 



Megistocrinus nodosus, Var. multidecoratus, Barris. 



Plate TI. — Fiff.j. Side view of an individual of medium size. 

 Fiff. 4. Ventral view of a smaller individual. 



This may be regarded as a variety of the former. While there is the 

 same general arrangement of plates, it is of a more robust make, and 

 attains a greater size. It is mainly distinguishable by the character 

 and extent of its ornamentation. In place of plates having a single 

 protruding central node, they have a series' of sharply defined points 

 or slight projections, regularly arranged so as to form noticeable sym- 

 metrical and sometimes even grotesque figures on the surface of the 

 plates. Nor is this arrangement confined mainly to the larger plates of 

 the calyx ; the higher and smaller plates have also their share of the 

 same kind of ornament. 



Whatever may be the character of the decoration on the first radial, 

 it is carried out to its fullest perfection on the second radials and first 

 interradials. less perfectly in each succeeding series of plates. 



In the preceding species are transitional forms that seem to look 

 forward to a different mode of ornamentation. In place of a single 



