LITHOSTROTION 



53 



beyond septa; tabulae appear very incom- 

 plete because of intersections of sinuous 

 septa. 



Occurrence. — Localities 1, 8, 9, 23, 

 55-57. 



Material. — Specimens studied, 33. Holo- 

 type, supposedly in Broadhead's collection, 

 probably was destroyed by fire. Specimens 

 examined, Illinois State Geological Survey 

 Nos. 3503, 3504, 3505, 3506, University 

 of Missouri Nos. 380, 1134, University of 

 Chicago Nos. 1243, 2037, 21295, 31587, 

 31594. 



Family Lithostrotiontidae (Grabau 

 1927) Chi, 1931 



Remarks. — The family Lithostrotiontidae, 

 proposed by Grabau in 1927 in an unpub- 

 lished syllabus used by students in the Na- 

 tional University of Peking, was first 

 published by Chi in 1931. 



Genus LiTHOSTROTiON Fleming, 1828 



Phaceloid and ceroid Rugose corals, which 

 have typically a columella, long major septa, and 

 large conical tabulae, usually supplemented by 

 outer smaller and nearly horizontal tabulae. Dis- 

 sepiments are well developed in the larger species, 

 but absent in the very small forms. Increase is 

 nonparricidal. (Hill, 1940, p. 166.) 



Genotype. — Lithostrotion striatum Flem- 

 ing, 1828. 



Occurrence. — Lower Carboniferous 

 through Lower Permian in Europe, Asia, 

 northern Africa, North America, and 

 Australia. 



Remarks. — The genotype was established 

 by the International Commission of Zoologi- 

 cal Nomenclature in Opinion 117. For a 

 review of the effects of this opinion, see 

 Hill (1940, pp. 166, 167). 



A large number of genera and subgenera 

 have been erected upon variations from typi- 

 cal Lithostrotion, but these subdivisions have 

 not all achieved ready acceptance. In the 

 case of Lithostrotion microstylum White, 

 the broad diagnosis of Lithostrotion applies, 

 but the species differs from Lithostrotion in 

 characters at least of equivalent value to 

 those used by some authors to name new 

 genera. It resembles Cystophorastraea 

 Dobrolyubova, 1935, in being partly cerioid 

 and partly aphroid, as well as in general 

 morphologic relationships of septa and 

 columella, but L. microstylum is not known 

 to have a thamnastreoid phase. 



The recognition of a very early Mississip- 

 pian Lithostrotion, further contradicts the 

 belief in America that the genus is an index 

 of St. Louis and Ste. Genevieve ages ; it has 

 been reported from rocks of possible Penn- 

 sylvanian age in Canada. The general range 

 of the genus abroad is very long, extending 

 through rocks equivalent to our Lower 

 Mississippian into rocks equivalent to part 

 of our Lower Permian. It may be expected, 

 therefore, that the range in America will be 

 further extended. 



Lithostrotion microstylum White 



Plate 13, figures 1-3; Plate 17, figure 1 



Lithostrotion microstylum White, 1880, U. S. 

 Geol. and Geog, Surveys Terr. 12th Ann. 

 Rept., pt. 1, Contr. Invertebrate Paleontology 

 no. 8, p. 159, pi. 40, fig. 7a, advance printing, 



Lithostrotion microstylum, White, 1883, idem, p, 

 159, pi. 40, fig. 7a. 



Lithostrotion microstylum, Keyes, 1894, Missouri 

 Geol. Survey, vol. 4, p. 124. 



non Lithostrotionella hemisphaerica Hayasaka, 

 1936, Mem. Fac. Sci. Agr., Taihoku Imp. 

 Univ., vol. 13, no. 5, p. 61. 



Externals. — Massive, somewhat flattened 

 coralla; calyces irregularly polygonal, about 

 1 cm across, shallow, with pronounced 

 central boss and surrounding raised ring 

 formed by elongation of septa; examples of 

 rapidly growing corallites overlapping neigh- 

 bors common. Corallites branching, nearly 

 recumbent on base, upturned at margin of 

 coralla ; holotheca not observed. Dimensions 

 of topotype, 3 cm by 9 cm by 11 cm. 



Transverse sections. — In mature region, 

 corallites plocoid, aphroid; lonsdaleoid re- 

 treat of septa variable; dissepiments irregu- 

 lar, generally large; septa strong, 18 reach- 

 ing columella becoming very thin near tips, 

 18 not quite reaching it at diameter of 8 

 mm ; columella circular, strong, with faint 

 radiating lines indicating incorporated tabel- 

 lae or septa; traces of tabulae well shown, 

 extending almost to tips of short septa. 



Longitudinal section. — Columella free, 

 solid rod with some vertical traces of tabel- 

 lae or septa; dissepiments irregular, ovoid 

 to commonly elongate parallel-bordered 

 vesicles two or three times as long as thick, 

 abruptly tapered at ends, sloping downward 

 axially at angle of about 45°, meeting at 

 border of corallites without intervening 

 epitheca ; where sections leave axial plane, 

 septa and dissepiments form more or less un- 



