32 



CHOUTEAU CORALS 



Tangential section. — (PL 3, fig. 2.) Sep- 

 ta slightly flexuous; carinae 6 in 3 mm, 

 very prominent, extending about 0.1 mm 

 from septa, with upward-directed hook at 

 tip, overlapping carinae of septa on either 

 side, but not exactly alternating with them, 

 being nearly opposed on any one septum but 

 lying in plane oblique through septum (ex- 

 cept in early ephebic stage, where carinae 

 alternate, slope downwards to septa). 



Transverse sections. — (PL 3, fig. 3.) In 

 middle ephebic stage (diameters 2.5 x 3.0 

 mm), septa thick, grouped somewhat in 

 pairs, five pairs on each side between single 

 thick cardinal septum and thin counter 

 septum with single minors joining it on 

 either side to form tripartite counter sys- 

 tem ; ends of septa fused in axis ; epitheca 

 thick ; tabulae sparse, thin ; occasional sep- 

 tal spine present. 



Broken tip in late neanic stage (diame- 

 ter 1.3 mm) with 8 septa united axially, 

 only two paired. 



Longitudinal section. — (PL 3, fig. 1.) 

 Axial structure with traces of sinuous septa, 

 especially in more mature stages ; carinae 

 slope gently downward axially; not more 

 than three very fine dissepiments observed. 



Comparison. — This species differs from 

 Lopholasma carbonaria Grabau and Metrio- 

 phyllurn battersbyi Edwards and Haime in 

 being notably smaller, having far fewer 

 septa, and in very rarely showing dissepi- 

 ments. 



Occurrence.- — Locality 7. 



Material. — Specimens studied, 3. Holo- 

 type. University of Cincinnati No. 24300; 

 paratypes, University of Cincinnati Nos. 

 24301, 24302. 



Genus RoTiPHYLLUM Hudson, 1942 



Densyphyllinn Thomson, 1883, Proc. Roy. Phil. 

 Soc. Glasgow, vol. 14, p. 445. 



Densiphyllum Vaughan, 1906, Quart. Jour. Geol. 

 Soc. London, vol. 62, p. 318. 



Densiphyllum, Vaughan, 1908, Quart. Jour. Geol. 

 Soc. London, vol. 64, p. 459. 



Densiphyllu7n, Smyth, 1915, Roy. Dublin Soc. 

 Sci. Proc, n. s., vol. 14, p. 556. 



non Densiphyllum Dybowski, 1873, Arch. Naturk. 

 Liv-, Esth-u. Kurl. [1], vol. 5, lief 3, p. 335. 



Rotiphyllum Hudson, 1942, Geol. Mag. vol. 79, 

 no. 5, p. 257. 



Rotiphyllum, Hudson, 1943b, Leeds Philos. Soc. 

 Proc. (Sci. Sec), vol. 4, pt. 2, p. 136. 



RotipJiyllum, Hudson and Fox, 1943, Yorkshire 

 Geol. Soc. Proc, vol. 25, pt. 2 (1942), p. 106. 



Diagnosis. — "Zaphrentoid corals of Fas- 

 ciculophyllum oinaliusi species-group^ with 

 evenly spaced, radial, major septa which 

 meet axially and form a stereocolumn. Car- 

 dinal fossula, on convex side of corallum, 

 similar to other loculi except that they 

 usually extend to the septal axis. Alar fos- 

 sulae indistinguishable from other loculi. 

 Tabulae conical. No dissepiments. Septal 

 plan in early growth-stages similar to that 

 in other species of F. omaliusi species- 

 group." (Hudson, 1942, p. 257.) 



Genotype. — Densiphyllum rushianum 

 Vaughan, 1908, emend. Hudson, 1943. 



Occurrence. — According to Hudson 

 (1943b, p. 137), "Rotiphylloid structures 

 are known in members of the F. omaliusi 

 species-group from the lower Tournaisian 

 to the top of the Visean." 



Remarks. — Rotiphyllum has not previ- 

 ously been identified in North America. 

 Both the American species studied herein 

 appear to be phylogenetically older than the 

 described British material in that the Amer- 

 ican species have wider stereocolumellae, 

 more prominent fossulae, pronounced bilat- 

 eral symmetry, and a tendency toward pin- 

 nate septa in the cardinal quadrants. 



Rotiphyllum calyculum (Miller) 

 emend. Easton 



Plate 3, figures 7-10; Plate 16, figures 32, 33 



Zaphrentis calyculus Miller, 1891, Indiana Dept. 



Nat. Res. 17th Ann. Rept., p. 10, pi. 1, figs. 



13, 14, Adv. Sheets. 

 Zaphrentis calyculus. Miller, 1892, Indiana Dept. 



Geol. Nat. Res. 17th Ann. Rept., p. 620, 



pi. 1, figs. 13, 14. 

 Zaphrentis calycula, Moore, 1928, Missouri Bur. 



Geol. Mines, ser. 2, vol. 21, p. 97. 



Externals. — Holotype curved trochoid, 

 widely flaring at calyx; calyx deep with 

 concave floor ; epitheca thin with striae ; 

 holotype has 25 primaries alternating with 

 short secondaries ; tips of majors fused to 

 central smooth area; first pair of majors 

 on each side of cardinal septum fused before 

 meeting smooth area; a short major on 



- ""The characteristic features of this group_ of small 

 conical, and curved Rugose Corals are the position of the 

 cardinal sectors on the convex side of the corallum, the 

 palmate grouping of the septa which are radial or 

 sli'^htly concave to the cardinal septum, the stereocolumn 

 o*^ varying strength, the pseudofossula about a counter 

 septum often long and rhopaloid, and the tendency of the 

 minor septa to be contratingent with the counter-minor'" 

 longer." (Hudson, 1943b, p. 104.) 



