Dec, 1920] Cystids and Blastoids 73 



20. Periechocrinus cylindricus Foerste. 



(Plate III, Fig. 4.) 



Periechocrinus cvlindriciis Foerste, Ohio Jour. Sci. 17, 1917, p. 244, PI. 10, 

 Figs. 1 A, B. 



In the museum of Wittenberg College, at Springfield, Ohio, there is a 

 calyx of Periechocrinus cylindricus nearly 80 mm. in length. Above the 

 distichals the individual plates are not outlined clearly, but it is evident 

 that in the case of each ray that part of the calyx which is directly above 

 the first pair of distichals is somewhat tumid for a height and width of 

 13 or 14 mm., thus giving the top of the truncated calyx a somewhat 

 pentagonal outline. Since only casts of the interior of the calyx are at 

 hand, it is impossible to determine how large was the column at its 

 attachment with the base of the calyx, but, as far as may be determined 

 from the form of the base of the cast of the interior, the diameter of 

 this column must have been small, almost too small to support a calyx 

 of such large size. 



EXPLANATION OF PLATES. 

 PLATE I. 



Fig. 1. Ccelocyslis suhglohosus (Hall). 



A, anal side, with the two posterior rays, each branched. Small lateral 

 branches of the main food-grooves alternate from side to side of the latter and 

 lead to the facets supporting the brachioles. The margin of the anal orifice pro- 

 trudes slightly. The attachment area for the column is 10 mm. in diameter. 

 B, viewed from above, with the anal orifice at the top. Both views drawn from a 

 wax cast of the hollow interior of a matrix preserving an impression of the exterior 

 of a complete theca. Only the wax cast is known at present, but the cast shows 

 plainly the presence of the cracks between the original rock fragments. No. 22906, 

 in the Hindshaw collection, in the Walker Museum, at Chicago University. From 

 the Racine dolomite at Chicago, Illinois. 



Fig. 2. Crinocystites chrysalis Hall. 



A, lateral view of cast of interior of an anal tube of some Calyptocrinid, 

 regarded by Hall as the theca of some cystid. B, posterior view of the same. Both 

 figures are reproductions of the figures accompanying the original description, in 

 20th Rep. New York State Cab. Nat. Hist., 1868, p. 318, PI. 12a, Figs. 10, 11, but 

 are published in a position inverted as compared with the original to indicate 

 their position in the Calytocrinid. From the Racine dolomite at Racine, Wis- 

 consin. The type, numbered 2023, is preserved in the American Museum of Natural 

 History. 



Fig. 3. Crinocystites chrysalis Hall. 



A, posterior view of cast of interior of an anal tube of some Calyptocrinid. 

 When found this cast of the interior was still attached to the matrix of the specimen 

 used for Figure B, which is an impression of the exterior of the same anal tube. 

 Figure B was drawn from a clay cast of this natural impression. It shows the 

 anterior or slightly concave side of part of the anal tube. The base of this figure 

 shows the upper extensions of the wing-like expansions forming the compartments 

 between which the arms of the Calyptocrinid are folded when at rest. Specimens 

 numbered 22914, from the Hall collection in Walker Museum at Chicago Uni- 

 versity. From the Racine dolomite at Racine, Wisconsin. 



