52 THE DEVONIAN OF MISSOURI. 



1 2 



Fig. 3. Sections of Chono phylum ellipticum Hall. 



1. A vertical section of a corallite from the bottom of the cup to two centi- 

 meters below the bottom. (X3/2.) 



2. A cross section 4 centimeters below the margin of the cup of the specimen 

 figured on plate 1, fig. 2. This section corresponds to a place about one-third 

 the distance from the bottom of figure 1. (X3/2.) 



Section of Diplophyllum callawayensis Branson 



3. A cross section about 4 centimeters from the base. (X3/2.) 



Genus Acervularis Schweigg 



Acervularia davidsoni Edwards and Haime 



Plate 4, figures 9 and 10. 



1851. Acervularia davidsoni, Edwards and Haime, Polyp. Foss. des. Terr. Palaeoz, 



p. 418, pi. 9, figs. 4, 4a and 4b. 

 1858. Acervularia profunda Hall, Geol. Surv. Iowa, I, pt. 2, pp. 477-478, pi. 1, figs. 



7, a, b, c. 



1858. Acervularia davidsoni? Hall, Geol. Surv. Iowa, I, pt. 2, pp. 476-477, pi. 1, figs. 



8, a, b. 



1876. Cyathophyllum davidsoni Rominger, Geol. Surv. Michigan, III, pt. 2, p. lOV, 



pi. 37, fig. 4. 

 1885. Cyathophyllum davidsoni Davis, Kentucky Fossil Corals, pt. 2, pi. 93, fig. 2; 



pi. 113, fig. 3. 

 1892. Acervularia davidsoni Calvin, Am. Geologist, vol. 9, pp. 355-358. 

 1894. Acervularia davidsoni Keyes, Pal. Missouri, pt. 1, Mo. Geol. Surv. IV, pp. 104- 



105. 

 1900. Acervularia davidsoni Lambe, Cont. to Canadian Pal. IV, pt. 2, pp. 164-165, 



pi. 14, fig. 3. 

 1909. Acervularia davidsoni Grabau and Shimer, North American Index Fossils, I, 



p. 69, fig. 106. 

 1911. Acervularia davidsoni Cleland, Wisconsin Geol. Nat. Hist. Surv. Bull. 21, p. 30, 



pi. 1, figs. 3 and 4. 

 1918. Acervularia davidsoni Branson, Geology of Missouri, pp. 100-101, pi. 3, fig. 8. 



Hall's description — "Coral astraeiform, subhemispheric; cells irregularly polygonal, 

 unequal in size, often somewhat circular in the young and half-grown conditions; walls 

 thin, scarcely undulating; inner wall undefined, cup abruptly and deeply depressed 

 from a little within the outer wall; centre marked by a papilliform mode." 



Calvin's description — "The calyces have a sharply defined central pit with explanate 

 margins. In typical specimens the floor of the calyx, except in the central pit, is almost 



