670 GEOLOGICAL SURVEY OP IOWA. 



subradial plates, and the one on the right of the anal plates 

 resting on the truncated upper face of a subradial plate, two 

 of its sides supporting two anal plates : the articulating 

 surfaces occupy the entire width of the plate. Second radials 

 quadrangular, wider than long, .the succeeding plates gra- 

 dually becoming wedgeform above. Arms long ; ( in two spe- 

 cimens examined) bifurcating on the thirteenth plate above 

 the second radial, and again at a higher point. Proboscis 

 elongate, composed of transverse hexagonal plates. Suture 

 lines between the plates of every second range marked by 

 rows of minute pores. 



COLUMN long cylindrical, enlarging near the base of the 

 calyx, with $ pentapetalous canal. 



This species is described by Dr. SHUMARD as having a column two feet in length. 



Fig. 7 a. A specimen showing the anal side, with a few joints of the column and the 

 lower part of the arms, and a part of the proboscis. 



Fig. 7 b. Enlargement of the plates of the proboscis, showing the pores between the 

 alternate ranges. 



Geological position and locality. In the St. Louis limestone, near St. 

 Louis, Missouri. 



Scapliiocrinus- dactyliformis ( n. s.). 



PLATE XVII. FIG. 6. 



BODY broadly subturbinate, wider at the summit than the 

 length. Basal plates small, pentagonal, longer than wide ; 

 subradial plates hexagonal, except on the anal side, about as 

 long as wide. First radial plates pentagonal, much wider than 

 long. Second radial plates pentagonal, a little longer than 

 wide : arms originating in pairs on the upper sloping sides 

 of the second radial, composed of strong thick plates with 

 alternating longer and shorter sides, and bifurcating on the 

 fourth plate from the base in some of the arms. 



COLUMN composed of alternating thicker and thinner joints 

 near the base of the body, becoming more unequal below, 

 every fourth or fifth plate being larger than the others. 



