INVERTEBRATES. - 237 



g- • This species is more nearly allied to C. rotxmda- 



tus, of Hall, {Iowa Report, vol. I, part ii, p. 555, 

 pi. 9, fig. la and' 7b), than to any other with 

 which we are acquainted. It differs, however, in 

 1, heing broader in proportion to its height, and is 

 moie nearly of the same height on the anterior 

 and posterior sides. Its plates are also propor- 

 tionally thinner, while the depressions in the upper 

 margins of its first radial plates are more shallow, 

 and not near so much beveled. Another marked 

 difference is the peculiar character of its sutures 

 Cyathocrinus Saffordi.— (Nat. size.) which are indicated by a distinct, raised line. Its 

 This cut shows the form and ar- fi rst a nal plate likewise differs in being truncated 



rangement of the basal, subradial, * ° 



first radial, and anal pieces. ver y nearly on a level with the first radial on each 



side, instead of projecting above. They are both very irregular forms, in 

 which the columnar facet is much nearer the anterior than posterior side. 



The specific name of the form under consideration was given in honor of 

 Prof. Safford, the State Geologist of Tennessee. 



Locality and position: White's Creek Springs, Tennessee; Keokuk limestone. 



Genus POTERIOCPJNUS, Miller. (See page 179.) 

 Subgenus SCAPHIOCUINUS, Hall, 1858. 



(Iowa Report, vol. i, part 2, p. 550.) 



Subgeneric formula. — 



Basal plates, 5. 



Subradial plates, 5. 



Radial plates, 2+5=10 ; r sometimes more than 2 in anterior ray. 



Anal plates, 1 to 6, or more. 



Interradial plates, 0. 



Arms, 2 -J- 5=10, two from each ray, simple or bifurcating. 



This group agrees in nearly all its essential characters with 

 Troost's genus Zeacrinus, so far as the number and arrange- 

 ment of its parts are concerned, but differs from most of the 

 species of that genus, in having its body obconical, or produced 

 so as to show the basal pieces in a side view, instead of con- 

 cave. It also differs in having the second radials and the 

 lower arm joints proportionally longer, and contracted on the 



