30 



CHOUTEAU CORALS 



Cyathaxonia arcuatus Weller is not re- 

 viewed in this study because the writer be- 

 lieves this species to be misidentified when 

 listed from beds lower than the Fern Glen. 



Cyathaxonia tantilla (Miller) 

 emend. Easton 



Plate 6, figures 7, 8; Plate 16, figures 16, 17 



Zaphrentis tantilla Miller, 1891 [in part], In- 

 diana Dept. Geol. Nat. Res. 17th Ann. Rept, 



p. 11, pi. I, figs. 23, 24. Adv. Sheets. 

 Zaphrentis tantilla, Miller, 1892 [in part], In- 

 diana Dept. Geol. Nat. Res. 17th Ann. Rept, 



pp. 621-622, pi. I, figs. 23, 24. 

 Zaphrentis tantilla, K,eyes, 1894, Missouri Geol. 



Survey, vol. 4, p. 111. 

 Zaphrentis tantilla, Keyes and Rowley, 1897, 



Proc. Iowa Acad. Sci., vol. 4, p. 30. 

 Cyathaxonia minor Weller, 1909, Geol. Soc. 



America Bull., vol. 20, p. 270, pi. 10, figs. 



14-17. 

 Cyathaxonia minor. Snider, 1914, Jour. Geol., 



vol. 22, no. 6, p. 17. 

 ^Cyathaxonia minor, Girty, 1915, U. S. Geol. 



Survey Bull. 598, p. 29. 

 C[yathaxonia] minor. Snider, 1915, Oklahoma 



Geol. Survey Bull. 24, p. 23. 

 Cyathaxonia minor, Purdue and Miser, 1916, 



U. S. Geol. Survey Folio 202, p. 11. 

 Cyathaxonia minor, Moore, 1928, Missouri Bur. 



Geol. Mines, ser. 2, vol. 21, pp. 148, 163, 191, 



195. 

 Cyathaxonia minor, Croneis, 1930, Arkansas 



Geol. Survey Bull. 3, pp. 47, 49. 

 Cyathaxonia minor, Cline, 1934, Amer. Assoc. 



Petrol. Geol. Bull., vol. 18, no. 9, pp. 1140, 



1144. 

 Cyathaxonia tantilla. Grove, 1935, Am. Midland 



Naturalist, vol. 16, pp. 367, 368, pi. 9, figs. 



15-17. 



Cyathaxonia tantilla, Moore, 1928, Missouri Bur. 

 Geol. Mines, ser. 2, vol. 21, pp. 53, 93, 96, 97, 

 120, 154, 195. 



Description. — Small, curved cylindrical, 

 commonly geniculate corallites; calyx deep, 

 with prominent elliptical axial boss, sharp 

 but short septa lining nearly vertical walls ; 

 epitheca moderately thick, very finely striate 

 to rugate, obscure septal grooves when un- 

 weathered. 



Transverse sections. — In late ephebic 

 stage (diameter 2.7 mm), 24 septa — one 

 cardinal, one counter with simple septum on 

 either side, then 5 pairs of septa on each 

 side uniting just short of columella; col- 

 umella practically undifferentiated, one- 

 fourth of diameter of calyx, slightly ellip- 

 tical, long axis directed counter-cardinally, 

 fused with tips of septa; septal spines very 

 rare. 



Most advanced stage observed (diameter 

 3.5 mm) with 28 septa lining walls of calyx. 



Broken tip in early ephebic stage (dia- 

 meter 1.3 mm) with 21 septa, cardinal, 

 counter and one lateral septa all single, 

 four pairs of septa on one side, five on other ; 

 extra pair on side of acceleration during 

 geniculation. Small spines abundant on sides 

 of septa. 



In neanic stages precise structure obscure ; 

 at 0.9 mm about 10 or 12 septa, columella 

 present. 



In general, paired septa consist of one 

 main septum and shorter auxiliary joining 

 on side away from cardinal septum. 



Longitudinal section. — Columella extend- 

 ing well into calyx ; septal spines quite prom- 

 inent, in arched series sloping inward and 

 downward ; dissepiments not observed ; tab- 

 ulae extremely thin, about 0.7 mm apart, 

 sloping gently upward axially. 



Occurrence. — Localities 2, 4-7, 46, 50, 

 52-54, 56, 60, ?61, 64, 75, 84, 98. This 

 species has also been reported from the 

 Burlington limestone at Louisiana and Han- 

 nibal, Missouri, by Keyes (1894, p. Ill), 

 but according to McQueen^ there are no 

 specimens listed in the Missouri Geological 

 Survey collection to substantiate this report. 



Material. — Specimens studied, 68. Holo- 

 type, University of Cincinnati No. 3940; 

 paratypes. University of Cincinnati No. 

 3941, 24404; Grove's hypotypes, University 

 of Chicago No. 38042 ; other studied ma- 

 terial, United States National Museum not 

 numbered, Illinois State Geological Survey 

 Nos. 3509, 3516, University of Missouri 

 not numbered, and University of Chicago 

 No. 9855. 



Remarks. — Miller designated 31 speci- 

 mens as cotypes of this species. One cotype, 

 which most closely fits the original illustra- 

 tions, and which bears a different number 

 (University of Cincinnati No. 3940) is 

 hereby designated the holotype. This is 8.5 

 mm long and would be about 2.7 mm in 

 greatest diameter if the calyx were not 

 somewhat crushed. It has 26 septa and a 

 prominent columella in the 1.5 mm deep 

 calyx. The exterior is smooth near the tip 

 but is weathered near the calyx. This speci- 

 men and several others were cleaned by the 

 writer in order to establish the nature of the 



Correspondence, H. S. McQueen, August 26, 1942. 



