Dec, 1920] Cystids and Blastoids 39 



total of three rays. The supporting plates for the rays are 

 uniserial, and all brachioles are located on the left side of the 

 rays, when the latter are held so that their proximal parts are 

 nearest the observer. The chief difference of this new species of 

 cystid of the Thebes locality from Wellerocystis appears to be 

 in the character of its plates, the latter being coarsely radiate 

 with bold cuneate ridges, much coarser than in Amygdalo- 

 cystites florealis. The anal opening is located on the convexly 

 curved side of the unbranched primary ray. 



Dr. E. O. Ulrich has collected Comarocystites shumardi and 

 Echinosphaerites cf. aiirantium from the upper Kimmswick also 

 at Cape Girardeau, Missouri. Wellerocystis kimmswickensis 

 probably belongs to the same horizon but was found farther 

 north in Missouri, in Jefferson County. No trace of this upper 

 Kimmswick fauna has been found so far in northeastern 

 Missouri, in Ralls or Pike Counties. 



2. Hallicystis imago (Hall). 



(Plate I, Figs. 7, 8; Plate II, Figs. 7 A, B, C.) 



Apiocystites imago Hall, 20th Rep. New York State Cab. Nat. Hist., 1868, 

 p. 314, PI. 12, Fig. 12, PI. 12a, Fig. 9. 



Hallicystis imago Jaekel, vStammesgeschichte d. Pelmatozoen, 1, Thecoidea 

 u. Cystoidea, 1899, p. 288, PI. 15, Fig. 3. 



Hallicystis elongata Jaekel, Idem, p. 288. 



Hallicystis imago Foerste, Ohio Jour. Sci., 17, 1917, p. 235, Fig. 1; PI. II, Fig. 2. 



Typical Hallicystis imago seems to be characterized by an attenuate 

 base for the attachment of the column, the attachment area being small 

 compared with that of Callocy stiles jewetti-elongatus. The pectinirhombs 

 appear to be narrow with relatively few dicho-pores. These features 

 are shown even by the smallest, and presumabh^ youngest, specimens 

 (Plate I, Fig. 8) at hand. 



Hallicystis elongatus appears to be a broader form, less attenuate at 

 the base, with the anus occupying a relatively lower position; the 

 pectinirhombs are conspicuously larger, and the dichopores on plates 

 14-15 number about 14, which is distinctly more than in typical 

 Hallicystis imago. 



It has not yet been determined whether these forms are distinct 

 species or merely variations of the same species. This will require a 

 sufficient number of specimens to determine their range of variation. 



Locality and Horizon. — From the Racine dolomite at 

 Racine, Wisconsin, and in the Chicago area, in Illinois. Also 

 from the Cedarville dolomite at Cedarville, Ohio. 



