58 



CHOUTEAU CORALS 



than In the earlier stages. Thus, with varia- 

 tions, the generic characters of Squameo- 

 phyllum, Ethmoplax, and Cleistopora are all 

 contained within this one specimen. 



Squameophyllum is supposed to differ 

 from Cleistopora chiefly in lacking dia- 

 phragms and in having sloping walls, rather 

 than a convex floor in each corallite. Speci- 

 mens of Leptopora typa Winchell seldom 

 possess diaphragms, and aside from the coral- 

 lites having convex floors, resemble Squame- 

 ophyllum spumans very closely. Variation in 

 this Chouteau species is extreme, and some 

 sections show walls and visceral tissue 

 merged so closely that they cannot be dif- 

 ferentiated (like Squameophyllum'), where- 

 as other sections show marked differences 

 between wall and visceral structure (like 

 Cleistopora) . Typically reticulate structure 

 tends to be horizontal, sometimes markedly 

 so, and therefore the recognition of Ethmo- 

 plax is even further to be questioned be- 

 cause of the similarity between its genotype 

 and species of Cleistopora In the Chouteau. 



The writer Is unable to evaluate the tax- 

 onomic significance of epithecal scales. If 

 they are accretionary phenomena, such as 

 are known in Xenophora, they may very 

 well be coincidental structures. 



Because of the close similarity between 

 Cleistopora, Squameophyllum, and Ethmo- 

 plax, the writer does not consider these 

 genera to warrant separation, even though 

 this group may have wide limits of indi- 

 vidual variation. Some systematists may 

 wish to preserve Squameophyllum and 

 Ethmoplax as subgenera. Others may 

 wish to consider Cleistopora ramosa (Row- 

 ley) described here as the type of a new 

 genus of equal rank. In the opinion of the 

 writer, this latter course would be inadvis- 

 able because of the demonstrable relation- 

 ship. 



The course followed by the writer es- 

 tablishes a long stratlgraphic range for 

 Cleistopora, but Its species are certainly dis- 

 tinct enough to permit correlation. 



Cleistopora procera (Rowley) 



Plate 15, figure 5; plate 17, figures 8, 9 



Leptopora procera Rowley, 1901, Am. Geologist, 

 vol. 27, p. 349, pi. 28, fig. 37. 



Leptopora procera, Robinson, Connecticut Acad. 

 Arts Sci. Trans., vol. 21, p. 164. 



Description, — "The base of this coral 

 differs but little from Leptopora placenta, 

 being flattened and with large shallow cups 

 and a very wrinkled and rugose epithecal 

 under surface but in producing tall crowded 

 stems above by calicular budding. It differs 

 from all the species of Leptopora with which 

 the author Is acquainted. The stems spring 

 from the shallow cups below, are more or 

 less round, very rugose and distorted and, 

 crowding together at the top, the otherwise 

 round cups become polygonal. From the 

 calyx of one of the stems three small stems 

 arise. No septa are observable nor are 

 placenta, but the latter are surely present. 

 The cups are shallow and are pitted or cel- 

 lular in appearance." (Rowley, 1901, pp. 

 349, 350.) 



Occurrence. — Localities 28, 108. 



Material. — The species apparently is 

 based upon a single specimen in the Rowley 

 collection which the writer understands is 

 now unavailable for study. The plesiotype 

 is University of Chicago No. 9765. 



Remarks. — Until the type of this species 

 can be studied, the internal structure must 

 remain unknown. It Is probable that the 

 specimen illustrated on plate 17, figures 8 

 and 9, may be a young specimen of C. 

 procera. The specimen is not as expanded 

 vertically as the type appears to be, but the 

 habit is otherwise quite similar. The internal 

 structure Is seemingly no different from that 

 of C. typa. 



Cleistopora RAMOSA (Rowley) 

 . Plate 14, figures 4, 5 ; Plate 15, figure 6 



Leptopora ramosa Rowley, 1901, Am. Geologist, 



vol. 17, p. 349, pi. 28, fig. 36. 

 Leptopora ramosa, Robinson, 1917, Connecticut 



Acad. Arts Sci. Trans., vol. 21, p. 164. 



Externals. — Corallum massive, cerloid, 

 oblate, tending towards fasciculate in most 

 advanced (gerontic?) stage; epitheca thin, 

 with striae, well defined rugae ; calyces not 

 very deep, with broadly sloping vesicular 

 walls. Length of plesiotype 9.5 cm; greatest 

 breadth, 7.5 cm ; mean breadth about 5 cm ; 

 thickness, 3.5 cm. 



Transverse sections. — Corallites, poly- 

 gonal, 5 to 7 sided, separated by dense cren- 

 ulate walls, each about 0.3 mm thick, meet- 

 ing at well-defined zigzag medial line ; walls 

 Irregularly perforate; centers of corallites 

 filled with dense sclerenchyme penetrated 



