.■}4 Cincinnati Society of Xatural History. 



Cyclocystoides mundulus, n. sp. (Plate II., fig. 7.) 



[Ety. — Mundulus, neat, trim.] 



This species consists of thirty-two marginal plates, and is a little 

 less than one half inch in diameter. It is from Mr. Dyer's collection, and 

 is somewhat weather-worn. A magnifier shows radiations, from a 

 subcentral elevation to the interior side of the ring, which, no doubt, 

 belong to the ornamentation of the interior disk. The surface markings 

 of the outer rim are not preserved. It was found near Morrow, Ohio, 

 in the upper part of the Cincinnati Group. 



Cyclocystoides bellulus, n. sp. (Plate II.. fig. 10, natural size; 

 fig. lOo, magnified view.) 



[Ety.— 5e«;'?»s, beautiful.] 



The specimen from which the following description is drawn, has 

 been injured upon one side, so that all the marginal plates can not be 

 counted; fourteen plates are distinct, and the injured space is of the 

 length of four plates; we suppose, therefore, that it consisted of eigh- 

 teen plates, forming a circle, the diameter of which is about six tenths 

 of an inch. The outer rim is thin, and attached to the inner rim in a 

 groove. It is ornamented by two, three, or four scars to each plate. 



These scars consist of elliptical, mammillary elevations, surrounded 

 by a shallow canal. The inner rim is strongly tuberculated, and at 

 the disconnected joints, each piece is striated about two thirds of the 

 wa}^ from the margin to the middle of the rim. This rim appears to 

 have had a tubular canal, as well as a semicircular groove, upon the 

 inner and outer side. Pores are distinctly- observed passing from the 

 canal surrounding the mammillary elevations upon the outer rim, 

 through the inner rim to the inner semicircular groove. 



This species is distinguished from C. magmis, not only by the num- 

 ber of the marginal plates, but by the shape of the mammillai-y eleva- 

 tions, and ornamentation of the outer rim. It was found at Cincinnati, 

 Ohio, and is in Mr. Dyer's collection. 



In 1851, attention was first called to these fossil bodies by Prof. 

 James Hall, in Foster and Whitney's Report on the Lake Superior 

 Land District. He described and figured a specimen found in the 

 Hudson River Group, having twenty-nine plates, without proposing 

 any name for it. In 1858, Billings and Salter, in Canadian Organic 

 Remains, Decade 3, founded the genus CyclocystoideSj and figured and 

 described from the Trenton Group of Canada, C. halli, having 36 mar- 

 ginal plates, and C. davisi., from the Upper Llandovery rocks of Eng- 

 land, having 48 or 49 marginal plates. In 1865, Prof Billings figured 

 and described, in Paheozoic Fossils, Vol. I., C. huronensis, having 60 

 marginal plates, and found on Lake Huron, in the Hudson River 



