I 



New Species of Crinoidea and other Fossils. 211 



Anal plates, only one visible in the specimen whicli is used for 

 description ; this rests upon the side of the second radial plate of the 

 adjoining ray, and is irregularly pentangular and of medium size. 



Surface of body-plates smooth ; those of the arms irregularly con- 

 stricted, and somewhat zig-zag in arrangement. 



This species is distinguished from H. simplex Hall, by the struc- 

 ture of tlie body, the constriction below the origin of tlie free arms, 

 and in having the armlets rising only from every third plate, while 

 in H. simplex they rise from every second plate on opposite sides, 

 or every fourth plate on the same side. 



Formation and locality. In the limestones of the Hudson-river 

 group, at Cincinnatti, Ohio. From Mr. C. B. Dyer. 



Heteeoceinus laxus n. sp, 

 Plate 5, fig. 15. 



Body small, with long, comparatively stout, flexuous arms, which 

 give origin to strong armlets at regular distances on the opposite 

 sides. Calyx turbinate, strongly pentalobate in the upper part, but 

 little higher than the width of the upper margin. Basal plates pro- 

 portionally large, pentangular, width and height equal. First radial 

 plates higher than wide, the others of equal proportions, or wider 

 than high ; the adjacent margins united to the top of the second 

 radials in the anterior and left an tero -lateral rays, and to the top of 

 the third in the other rays, thus forming the calyx ; above this point 

 they become free. 



The bifurcation of the rays takes place on the fifth and sixth plate 

 above the basals ; beyond this point there are no true bifurcations, 

 the arms giving support to strong armlets on every fourth plate on 

 the opposite sides, or every eighth plate on the same side. Arm 

 plates quadrangular, height and width nearly equal. Armlet plates 

 long, quadrangular. 



There are indications at several points that the armlets also bifur- 

 cate at about the sixth or seventh plate. 



Anal plates, two visible in the specimen ; narrow, elongate, the 

 lower one resting upon the side of the second radial plate of the 

 adjacent rays. 



Surface of plates smooth or granulose. 



This is easily distinguished from the other species by the pentalo- 

 bate calyx, the serpentine direction of the arms, and the greater 

 number of plates between the armlets. 



Formation and locality. In the rocks of the Hudson-riyer group, 

 at Cincinnati, Ohio. From Mr. C. B. Dyer. 



