406 Proceedings of the Ohio State Academy of Science. 



its manner of preservation. Practically all of the specimens 

 are granular, calcite casts and when broken from the limestone 

 matrix the internal molds are sprinkled with a thin coat of these 

 crystals. These molds as a rule do not show the keel. 



This is one of the four most common species of the Alax- 

 ville limestone. It has a rather great vertical range and at cer- 

 tain horizons is found in large numbers. 



Horizon and locality. ■ — Maxville limestone. 

 Upper zone : North Bank of Jonathan Creek, Fultonham ; Glad- 

 stone Mills, Kroft Bridge, Thompson Residence, Below 

 Thompson Residence, White Cottage; Smith Chapel, Logan. 

 Shale-nodular zone : Cut No. 5, Upper end of Cut No. 6, Mouth 

 of Hough Hollow, Mt. Perry-Fultonham ; Kroft R.esidence, 

 Kroft Bridge, White Cottage ; Stimmel Residence, Max- 

 ville ; Smith Chapel, Logan. 

 Lower zone: Cut No. 4, Cut No. 5, Mt. Perry-Fultonham. 

 Undetermined zone : Middle of Cut No. 6, Mt. Perry-Ful- 

 tonham. 



ORTHONYCHIA ACUTIROSTRE— Hall. 



1856. Capuhis acutirostris. Hall, Trans. Albany Inst., Vol. IV, p. 31. 

 St. Louis limestones: Spergen Hill and Bloomington, Indiana. 

 1858. Capidiis acutirostris. Hall, Geol. Iowa, Vol. I, pt. II, p. 665, pi. 

 23, figs. 14a, b. 

 Warsaw limestone: Warsaw, Illinois; Spergen Hill and Bloom- 

 ington, Indiana. 

 1866. Platyceras imcum. Meek and Worthen, Proc. Acad. Nat. Sci. 

 Phil., p. 264. 

 Keokuk limestone : Nauvoo, Illinois. 

 1873. Platyceras unciim. Meek and Worthen, Geol. Surv. 111., Vol. V, 

 p. 516, pi. 17, fig. la, b. 

 Keokuk limestone : Nauvoo, Illinois. 



1882. Platyceras acutirostris. Whitfield, Bull. Am. Mus. Nat. Hist., Vol. 



I, p. 67, pi. 8, figs. 13-15. 

 St. Louis group : Spergen Hill, Paynter's Hill, Elletsville, Bloom- 

 ington and Crawfordsville, Indiana ; Warsaw, Illinois ; Tus- 

 cumbia, Alabama. 



1883. Platyceras acutirostris. Hall, Ind. Geol. Nat. Hist., 12th Rep., p. 



370, pi. 31, figs. 13-15. 

 St Louis group : Spergen Hill, Lanesville and Bloomington, In- 

 diana. 



