EAELY PALEOZOIC BEYOZOA OF THE BALTIC PROVINCES. 81 



Genus CERAMOPORELLA Ulrieh. 



Ceramoporella Ulrich, Journ. Cincinnati Soc. Nat. Hist., vol. 5, 1882, p. 156. — 

 Miller, North Amer. Geol. and Pal., 1889, p. 297.— Ulrich, Geol. Surv. 

 Illinois, vol. 8, 1890, pp. 380, 464; Geol. and Nat. Hist. Surv. Minnesota, vol, 

 3, pt. 1, 1893, p. 328.— PocTA. Syst. Sil. Centre Boheme, vol. 8, pt. 1, 1894. 

 p. 15. — ^Ulrich, Zittel's Textbook gf Paleontology (Eng. ed.), 1896, p. 

 267. — Simpson, Fourteenth Ann. Rep. State Geologist New York for the 

 year 1894, 1897, p. 564.— Nickles and Bassler, Bull. 173, U. S. Geol. Surv., 

 1900, p. 23.— Bassler, Bull. 292, U. S. Geol. Surv., 1906, p. 20.— Cumings, 

 Thirty-second Ann. Rep. Dep. Geol. Nat. Res. Indiana, 1907, p. 742. 



Zoarium of incrusting layers, which by superposition may forra 

 masses; zooecia short, tubular with thin walls; apertures oval, ob- 

 lique, the lunarium forming a hood; mesopores abundant, often com- 

 pletely encircling the zooecia. 



Genotype. — Ceramoporella distincta Ulrich. Upper Ordovician 

 (Eden and Maysville) of the Ohio Valley. 



Until recently this genus has included all of the parasitic Ordovi- 

 cian ceramoporoids, but the discovery of the foregoing Russian 

 species of incrusting, although otherwise typical Ceramopora in Ordo- 

 vician strata, causes this conception to be modified. Ceramoporella 

 includes two well-marked sections or groups of species, one in which 

 the zooecia are inclined to be rhomboidal or polygonal in outline and 

 more or less in contact, and another with rounded or ovate apertures 

 and numerous mesopores. One or more distinct species of each sec- 

 tion usually occur in each of the Ordovician formations, while a few 

 species are of such generalized types of structure that they range 

 through several formations and can be distinguished at best only as 

 varieties. The new variety following belongs to the latter category. 



CERAMOPORELLA GRANULOSA MINOR, new variety. 

 Text fig. 22. 



In 1890 Ulrich described a new species of Ceramoporella from the 

 Fernvale shale division of the Richmond group, at Wilmington, Illi- 

 nois, naming it C. granulosa ^ because of the numerous, acanthopore- 

 like granules occurring in the walls. Further study has shown that 

 this same species, variously modified, occurs in most of the Ordovi- 

 cian formations commencing with the Black River. Only one of 

 these varieties has received a name, but all of them differ from the 

 type form in minor detaUs only. Thus, the present form difl'ers only 

 in having slightly smaller zooecia and fewer granules. 



In the species itself as well as in the varieties^ the zoarium is in- 

 crusting a foreign body and by the superposition of several layers 

 forms masses of some size. The zoarial surface is smooth and granu- 

 lose, with the usual maculae. Zooecial apertures oval, opening at the 



1 Geol. Surv. Illinois, vol. 8, p. 466, pi. 41, figs. 2, 2 a. 



