36 



CHOUTEAU CORALS 



Longitudinal section. — Tabulae complete, 

 sharpl)^ recurved proximally near their bor- 

 ders in lower half of corallite, less sharply 

 recurved near calyx; dissepiments very 

 sparse, either in angle between a tabula and 

 epitheca or enlarged with tabulae butting 

 against them; about 7 tabulae in 10 mm. 



Comparison. — T. palmatus differs from 

 T. spin nl OS us a (Grove) in having the 

 cardinal septum shortened by early ephebic 

 stage; the pronounced palmate grouping of 

 septa in the counter quadrants, the very 

 strong counter septum, and the early reduc- 

 tion of the length of the cardinal septum 

 are characteristic of the species internally. 

 The generally trochoid shape, the very deep 

 calyx, the strong interseptal ridges, and the 

 sparse spines may provide external identify- 

 ing characters. 



Occurrence. — The specimens were col- 

 lected by the writer from near the top of 

 the Kinkaid limestone (Chester series, Mis- 

 sissippian system) in the gully to the west 

 of the road north of Cedar Grove Church, 

 in the NE. ^4 NW. >i sec. 31, T. 11 S., 

 R. 2 E., Johnson County, Illinois. The col- 

 lections came from bed 13 as measured by 

 Lamar (Illinois Geol. Survev Bull. 48, p. 

 80,1925). 



Material. — Holotvpe, No. 3519; figured 

 paratypes, Nos. 3520, 3521, 3522, 3523; 

 unfigured paratypes No. 3524; topotypes 

 No. 3525 ; all in the collections of the Illi- 

 nois State Geological Survey. The speci- 

 mens from which figs. 3a-3d and 4a-4c of 

 plate 8 were drawn were completely ground 

 away in an effort to obtain the earliest 

 possible stages. 



Remarks. — No other group of corals is 

 as difficult taxonomically as the so-called 

 "zaphrentids." Most identifications are 

 questionable when made without sections, 

 but even when sections are prepared, the 

 simple morphology is misleading. The most 

 recent nomenclatural advance has been the 

 restriction of Zaphrenthis {sensu stricto) 

 to corals with an open cardinal fossula, car- 

 inate or toothed septa, and a wide zone of 

 dissepiments (Schindewolf, 1938, p. 452). 

 No known Carboniferous corals are refer- 

 able to Zaphrenthis. 



Schindewolf (1938, p. 450) separated 

 the Carboniferous "zaphrentid" corals into 

 two subgenera under the genus Zaphren- 

 toides Stuckenberg, 1895. Of these, Zaph- 

 rentoides (Zaphrentoides) has the cardinal 



fossula on the convex side of the corallite 

 and Zaphrentoides (Hapsiphylluin) has the 

 cardinal fossula on the concave side of the 

 corallite. This taxonomic arrangement places 

 corals both with and without dissepiments 

 in the same subgenus, a condition which the 

 writer considers unsatisfactory. The pres- 

 ence or absence of a major morphologic fea- 

 ture, such as a tendency for development of 

 dissepiments, is of greater taxonomic value 

 than the orientation of an existing feature, 

 such as the cardinal fossula. Even so, the 

 writer essentially agrees with Schindewolf 

 that the dominent position of the cardinal 

 fossula has taxonomic significance, that its 

 significance is of subgeneric rank, and that 

 the mere presence of alar fossulae is not of 

 generic importance. 



Instead of adopting a modification of 

 Schindewolf's taxonomy, the writer feels 

 it necessary to establish a new genus whose 

 characters are referable to an incontrovert- 

 ible genotype which, in turn, is based upon 

 adequately known type material. T. palm- 

 atus is the best known species available to 

 the writer ; it is abundant at its type local- 

 ity which is well established, the material is 

 well preserved, and the species is entirely 

 typical of the genus. For these reasons, this 

 Kinkaid species is chosen as genotype, 

 rather than one of the Chouteau species, all 

 of which are less well known and either are 

 rarely found or are based upon unavailable 

 types. Several available genera may prove in 

 one or more cases to be senior sj'^nonyms of 

 Triplophyllites, in which instance it will be 

 small trouble to make necessary nomencla- 

 tural changes. As it stands, one must either 

 refer these species to a genus (Zaphrenthis) 

 to which they are known not to belong or 

 refer them to a genus whose characters are 

 inadequately known. The status of several 

 genera belonging in the latter category are 

 reviewed below. 



(1) Zaphrentoides Stuckenberg, 1895, 

 was proposed to include corals as follows: 

 "Simple corals whose corallites possess 

 more or less regular conical shape. On the 

 outer surface of the wall we percieve en- 

 circling swellings in faint impression. The 

 septa are separated into two cycles. The 

 septa of the first order extend almost to the 

 axis and are slightly twisted there ; are four : 

 the cardinal septum, the counter septum, 

 and alar septa [which are] weakly devel- 

 oped and situated in fossulae; of these ffos- 



