44 



CHOUTEAU CORALS 



Remarks. — The neanic sections described 

 above are from material collected from the 

 Burlington limestone. These sections differ 

 from the neanic section (slightly younger) 

 figured by Grove (1935, pi. 13, fig. 6) in 

 that they do not have the open central area 

 and accompanying short septa. 



Hapsiphyllum (Homalophyllites) 

 piNNATUS Easton n. sp. 



Plate 7, figures 6-8; Plate 16, figures 11-15 



, [in part], In- 

 17th Ann. Rept., 



Zaphrentis tenella Miller, 1891 



diana Dept. Geol. Nat. Res. 



p. 11, Adv. Sheets. 

 Zaphrentis tantilla Miller, 1891, [in part], idem, 



p. 11. 

 Zaphrentis tenella, Miller, 1892, Indiana Dept. 



Geol. Nat. Res. 17th Ann. Rept., p. 621. 

 Zaphrentis tantilla, Miller, 1892, [in part], idem, 



p. 621. 

 Zaphrentis tantilla, Keyes, 1894, Missouri Geol. 



Survey, vol. 4, p. 111. [ ?] 



Description. — Simple, sharp pointed, 

 curved ceratoid corals with geniculate tip 

 bent to right when cardinal fossula is 

 oriented downward ; calyx moderately deep, 

 calicular pit connected with very deep, 

 prominent cardinal fossula generally on 

 convex side ; septa increasing in length from 

 upper edge of calyx toward floor; major 

 septa 22 in calyx of holotype at late ephebic 

 stage, alternating with short minor septa 

 as septal ridges ; epitheca very thick, smooth, 

 obscuring interseptal ridges. 



Holotype large, 20 mm long, 8.0 mm in 

 diameter at calyx; most specimens about 

 13 mm long, 6 mm in diameter at calyx, 

 with 17 or 18 major septa. 



Holotype in late ephebic stage (diameter 

 8.0 mm) with radially arranged septa; 

 cardinal septum only slightly recessive, three 

 major septa grouped on each side, followed 

 by alar septa, a pair of majors, four majors, 

 and cardinal septum similar to others. 



In middle ephebic stage (diameter 5.8 

 mm), septa in quadripartite grouping with 

 septa of cardinal quadrants pinnate ; cardi- 

 nal septum fairly long; without axial pit 

 connecting with cardinal fossula; a pair of 

 major septa on either side of cardinal sep- 

 tum, followed by single major which may 

 or may not extend to center ; alars somewhat 

 longer than neighboring septa, followed by 

 pair, to which third is more or less joined; 

 single majors on either side of the counter, 

 which extends almost to axis. 



In early ephebic stage (diameter 1.2 mm), 

 13 or 14 septa; uncertain because of imper- 

 fect preservation in studied specimen. 



In early neanic stage (diameter about 0.9 

 mm) 9 septa; cardinal long, in prominent 

 pseudofossula, confluent with counter; alar 

 septa prominent. 



Longitudinal section. — Thin tabulae ris- 

 ing upward axially, about 1 mm apart. 



Co?nparison. — This species differs from 

 H. (Homalophyllites) calceolus in being 

 generally smaller, having a shorter cardinal 

 fossula in which the cardinal septum reaches 

 the axis, in having fewer septa, and in lack- 

 ing the flattening of the cardinal (convex) 

 side. 



Occurrence. — Holotype and paratypes, lo- 

 cality 9; other specimens, locality 1. 



Material. — Specimens studied, 10. Holo- 

 type, University of Cincinnati No. 24393 ; 

 paratypes. University of Cincinnati No. 

 24310; plesiotypes. University of Cincin- 

 nati Nos. 24390 ( formerly cotype of Z. tan- 

 tilla) , 24408 (as paratypes of Z. tenella)^ 

 and 24409 (as cotype of Z. calycula Mil- 

 ler) ; other plesiotypes (which were in the 

 same lot as the type of Z. exigua Miller), 

 University of Cincinnati No. 24391 ; fig- 

 ured plesiotype, Illinois State Geological 

 Survey No. 3502. 



Remarks. — This species is most interest- 

 ing because of the persistence of the long 

 cardinal septum into late stages and the 

 persistent pinnate arrangement of septa in 

 the cardinal quadrants. 



Genus Neozaphrentis Grove, 1935 



Diagnosis. — "Small to large conical to 

 sub-cylindrical solitary corals, curved or 

 nearly straight. Exterior rugose and may 

 be concentrically wrinkled and undulatory; 

 often annulated from rejuvenescence or pe- 

 riodic growth. Calyx shallow to deep. Septa 

 variable in thickness, smooth, non-carinate, 

 straight or distally wavering ; in two cycles, 

 but the secondaries may be rudimentary. 

 Not more than 60 major septa, not mar- 

 ginally contracted, extending to the center 

 of the calyx where they may fuse, or disap- 

 pearing a short distance before reaching the 

 center, which is then occupied by a small 

 open or tabulate area. Cardinal septum re- 

 cessive in post-neanic stages. Cardinal fos- 

 sula well developed, variable in position, 

 sub-central or extending to the margin. Tab- 



