176 PROCEEDINGS OF THE ACADEMY OF [1890. 



Horizon and locality. Keokuk shales : Crawfordsville, Indiana. 



This species occurs in the famous Crawfordsville crinoid beds, as- 

 sociated with C. equilateralis and C. infundibulum both of which are 

 common species of that locality. It is one of the few regularly 

 costate species of the genus and the only one of this character found 

 in the Carbonic strata of America. 



Capulus ovalis (Stevens). 



Acroculia ovalis Stevens, 1858. Am. Jour. Sci , (2), vol. xxv, p. 261. 



Platyceras laevigatum Meek & Wortlien, 186C. Proc. Acad. Nat. Sci , Phila., 

 1866, p. 263. (Not Acroculia hcvigata McCoy.) 



Shell very small, subglobose ; volutions about two an one-half in 

 number, contiguous, rather rapidly expanding but not campanulate ; 

 spire very small. Aperture regularly subcircular or oval, but 

 frequently somewhat flattened laterally ; lip sharp, not sinuous. 

 Surface glabrate ; but under the magnifier exhibiting fine regular 

 lines of growth. 



Horizon and localities. Ka.skaskia limestone : Union and Ran- 

 dolph counties, Illinois ; St. Genevieve county, Missouri. 



Capulus ovalis is one of the smallest of the lower Carbonic (Japuli, 

 having a height of only three to six millimeters and a maximum 

 breadth of eight millimeters. 



Capulus chesterensis (Meek <fe AVorthen). [Plate 11, tigs. l?.a, 13b, 13c, 13d.] 



Platyceras ( Orf/ionyc/iia) chesterense Meek & Wortlien, 1866. Proc. Acad. Nat. 

 Sci., Phila., 1866, p. 265. 



Platyceras chesterense Keyes, 1888. Proc. Am. Philosophical Soc, vol. XXV 

 figs. 4 and 5. 



Ci7/«/«j (7/«.V;-(f;/.w Keyes, 1890. Am. Geologist, vol. V. 



Shell small, obliquely conical, with five nearly equidistant, longi- 

 tudinal furrows, which alternate with broad flattened folds ; expand- 

 ing moderately to the aperture ; usually more or less strongly arcu- 

 ate, sometimes forming nearly half of a volution, thus bringing the 

 apex above or even considerably beyond the posterior portion of the 

 labrum. Apex more or less attenuated but often blunt. Aper- 

 ture pentagonal, or irregularly subcircular ; lip thick, rounded, with 

 five deep, rounded sinuses. Surface marked by numerous subimbri- 

 cated, broadly undulating lines of growth. 



Horizon and localities. Chester division of the Lower Carbonic : 

 Chester and Pope counties, Illinois ; and Pulaski county, Kentucky. 



This little species is found almost invariably attached to the vault 

 of crinoids ; and Meek & Worthen report one adhering to the side 

 oi Pentremites godoni DeFrance, "so as to entirely cover one of the 



