406 Proceedings of the Ohio State Academy of Science. 



its manner of iM-eservation. I'racticall\- all of the specimens 

 are granular, calcite casts and when broken from the limestone 

 matrix the internal molds are sprinkled with a thin cat 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. 



Horicon and locality. — Maxville limestone. 

 Upper zone: North I'ank of Jonathan Creek, Fultonham ; Glad- 

 stone Mills, Kroft Bridge, Thompson Residence, Below 

 Thompson Residence, White Cottage ; Smith Chapel, Logan. 

 Shale-nodular zone: Cut Xo. 5, Upper end of Cut Xo. 6, Mouth 

 of Hough Hollow, ]\It. Perry-Fultonham ; Kroft Residence, 

 Kroft Bridge, White Cottage ; Stimmel Residence, Max- 

 ville ; Smith Chapel, Logan. 

 Lower zone: Cut Xo. 4, Cut X\:). 5, Mt. Perry-Fultonham. 

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

 tonham. 



ORTHONYCHIA ACUTIROSTRE— Hall. 



1856. Capiiliis aciitirostris. Hall, Trans. Albany Inst., Vol. IV, p. 31. 

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

 1858. Capidus aciitirostris. 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 uncnni. Meek and Worthen, Proc. Acad. Nat. Sci. 

 Phil, p. 264. 

 Keokuk limestone : Nauvoo, Illinois. 

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

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

 Keokuk limestone: Nauvoo, Illinois. 



1882. Platyceras aciitirostris. 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 aciitirostris. Hall, Ind. Geol. Nat. Hist., 12th Rep., p. 



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

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

 diana. 



