No. 189.] 57 



Arms composed of a single series of plates which are alternately 



. longer and shorter on the opposite sides, bearing strong ten- 



tacula on the upper part of the longer side. 

 The anal area has apparently three plates attached to the calyx, 



while the upper part of the area is not visible in the specimens 



examined. 

 Surface smooth. 



POTEEIOCRINUS PLEIAS ( n s.). 



A SPECIES of small or medium size. 



Body somewhat broadly turbinate, or expanding in the upper 

 part. Basal plates very short ; the subradial and radial plates 

 comparatively short. The second radial is about as wide as 

 long, supporting on each upper sloping face an arm, which is 

 simple to the eighth plate ; above which, they are unknown. 

 The arms are composed of a single series of long subcuneiform 

 plates, which bear tentacula on their longer sides. The anal 

 plates are small and numerous, extending upwards into the 

 proboscis. 



Surface smooth or very finely granulose. 



Column subpentagonal, composed of alternating thicker and 

 thinner plates. 



This resembles the P. crineus, but is more slender in its form and structure. The 

 arm-joints are proportionally longer than in that one. 



POTEEIOCRINUS CORYCIA ( n. s.). 



A SPECIES with a small, short, and somewhat broadly turbinate 

 body. The basal plates are wider than high, pentangular. Sub- 

 radial plates proportionally large : first radial plates once and 

 a half as wide as high. The second radial plates are as high or 

 higher than wide on the antero-lateral and postero-lateral rays, 

 and supporting on their upper sloping faces, arms which bifur- 

 cate on the tenth plate above, with probably a second bifurca- 

 tion above this one. The second radial of the anterior ray is 

 twice as long as w^ide, truncate above, and supporting a single 

 arm which bifurcates on the fourth plate above, giving six 

 plates in the ray below the bifurcation, Anal plates unknown. 



Surface somewhat strongly granulose. 



This species bears considerable resemblance to P. cauliculus of the Burlington 

 limestone, but differs essentially in the structure of the arms. 



SUBGENUS SCAPHIOCRINUS. 



SCAPHIOCRINUS (POTERIOCRINUS) iEGINA (n.s.). 



Body shortly turbinate or subhemispheric. Basal plates very 

 short, triangular : subradials about as wide as long, a little 

 smaller than the first radial plates. Radial series consisting of 

 [Assem. No. 189.] 8 



