Dec, 1920] Cystids and Blastoids 55 



the anterior angle- to the posterior margin. From the five angles ridges 

 extend toward the center of the rather flat top of the protuberance. 

 These 5 ridges are not sharply defined and their actual structure remains 

 obscure. There is no evidence of the presence of food-grooves. As far 

 as may be determined from the single specimen at hand, the oral aperture 

 may have been covered by a pyramid of 5 plates, somewhat as in 

 SphcBronis, globidus Angelin, or as in Glyptosphara leuchtenbergi Volborth, 

 from the Ordovician of the Baltic areas of Russia. 



Between the oral and the anal apertures there is a transverse ridge, 

 interpreted as locating the madreporite. No gonopore can be detected. 



The margin of the anal aperture protrudes slightly. Its outline is 

 shghtly elliptical, rather than circular, the diameters being 3 and 4 mm. 

 The inner margin appears to be rhomboid with the major axis in a 

 lateral direction, suggesting an anal pyramid of 4 plates, but the evidence 

 is not clear. 



Surface granulose, with the granules varying from slightly more to 

 sHghtly less than a millimeter apart. Under a lens, very minute gran- 

 ules, not visible to the unaided eye, appear in great numbers. Where 

 the surface of the plates has been removed in cleaning the top or fifth 

 circlet of plates, there appear to be slight color changes suggesting the 

 presence of the Omega-like ornamentation of the worn surfaces of the 

 plates of Holocystites. Here, again, the evidence is not clear. 



Locality and Horizon. — From the Osgood formation on 

 Riker's Ridge, about 4.5 miles northeast of Madison, Indiana. 

 Type numbered 6006 in Walker Museum of Chicago University. 



Remarks. — Were it not for the oral protuberance, this spec- 

 imen would be regarded readily as a typical species of Holo- 

 cystites. It differs in plate system from such a form as Holo- 

 cystites greenvillensis chiefly in the presence of numerous acces- 

 sory plates. It is regarded as belonging to the same family. 

 However, the anomalous oral protuberance is suflticient to estab- 

 lish it as a distinct genus. 



fc>^ 



10. Gomphocystites indianensis Miller. 

 (Plate I, Figs. 5 A, B.) 

 Gomphocystites indianensis Miller, N. Amer. Geol. Pal., 1889, p. 249, Fig. 319. 



The upper, more globular part of the theca evidently has been 

 compressed, but its outline, as seen from above, may have been distinctly 

 elliptical even before compression. This is suggested by the relatively 

 straight direction of the anterior and right anterior food-grooves along 

 part of their paths, as seen in the figure accompanying the original 

 description of the species. It is suggested also by the parallel direction 

 of the straight parts of these food-grooves and by the angular curvature 

 of the right anterior food-groove at mid-length. It will require addi- 

 tional specimens to determine how much of the elliptical form of the 



