PALEONTOLOGY OF IOWA. 627 



FIG. 99. 



The accompanying diagram repre- 

 sents the form and proportions of 

 the plates of the body of this species, 

 including the first plates of the arms 

 on three of the rays. 



Geological formation and locality. In the Keokuk limestone : Warsaw, 

 Illinois. 



Cyathocrinus intermedius ( n. s.). 



PLATE XVIII. FIG. 10. 



CUP narrow subturbinate. Basal plates wider than long, 

 slightly spreading from the top of the column. Subradials 

 longer than wide, very gradually widening from the base to 

 the upper margins. First radial plates nearly twice as wide 

 as long : second and third radials unknown. Arm-plates 

 nearly as long as wide : arms bifurcating several times. 



COLUMN large, gradually tapering below the base, consisting 

 of alternating thicker and thinner joints, which are deeply 

 striated upon their articulating surfaces. 



This species has the aspect of POTERIOCRINUS, except in the character of the anal 

 plates. In the arrangement shown in this one and two other species of apparently 

 true CYATHOCRINUS, there is an intercalated quadrangular plate lying between the 

 right subradial and the succeeding radial, dnd between the first anal plate and the 

 subradial plate below : this plate is so small, that it allows the lateral edges of the 

 radial and first anal proper to meet; and in this respect differs from the typical 

 POTERIOCRINITES, as shown in the diagram, illustrative of the generic formula, by 

 DE KONINCK and LE HON. For this reason, I retain the species under CYATHOCRINUS. 



Fig. 10. The anal side of specimen, which is much crushed and the plates separated. 



Geological formation and locality. In the Keokuk limestone : Warsaw, 

 Illinois. 



