272 BULLETIN 11, UNITED STATES NATIONAL MUSEUM. 



Occurrence. — Abundant in the Kuckers shale (C2) at Keval; less 

 common in the Kegel limestone (D2) at Kegel, Esthonia; rare in the 

 limestone with Trinucleus seticornis near Hulterstad Church, island 

 of Oeland. 



Cotypes.—Csit. No. 57375, U.S.N.M. 



British Museum, specimens from Reval, Esthonia, and from the 

 island of Oeland. 



Genus BATOSTOMA Ulrieh. 



Batostoma Ulrich, Joum. Cincinnati Soc. Nat. Hist., vol. 5, 1882, p. 154. — 

 FooRD, Contr. Micro-Pal. Cambro-Sil., 1883, p. 17. — Miller, North Amer. 

 Geol. and Pal., 1889, p. 294.— Ulrich, Geol. Surv. Illinois, vol. 8, 1890, pp. 

 379, 459; Geol. and Nat. Hist. Surv. Minnesota, vol. 3, pt. 1, 1893, p. 288; 

 Zittel's Textbook of Paleontology (Eng. ed.), 1896, p. 275. — Simpson, Four- 

 teenth. Ann. Rep. State Geologist of New York for the year 1894, 1897, 

 p. 588.— NiCKLES and Bassler, Bull. 173, U. S. Geol. Surv., 1900, p. 35.— 

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

 p. 740. 



This genus is most prolific both in species and specimens, but seems 

 to be limited to Ordovician strata and to the Richmond formation 

 of the earliest Silurian. In America no less than a dozen species 

 have been described from the Middle Ordovician alone, and a number 

 of new forms are known. Four of these same forms occur in the 

 Russian deposits with a few new species. The essential characters 

 of the genus are embodied in the following description: 



Zoarium irregularly ramose, branches arising from a large basal 

 expansion; zooecia with walls that are thin in the immature region, 

 much thickened and in sections appearing rmg-like (but seldom in 

 contact) in mature region; diaphragms present; mesopores numerous 

 or few, irregular in size or shape; acanthopores usually of large size 

 and abundant, sometimes few. 



Genotype. — Monticulipora (Heterotrypa) implicata Nicholson. Upper 

 Ordovician (Eden) of the Ohio Valley. 



BATOSTOMA MAGNOPORA. Ulrich. 



Text figs. 161, 162. 



Batostoma magnopora Ulrich, Geol. and Nat Hist. Surv. Minnesota, vol. 3, 

 pt. 1, 1893, p. 261, pi. 25, figs. 12-15. 



Original description. — This is given by Ubich as follows : 



Zoarium ramose; branches large, subcylindrical, 8 to 15 mm. wide; surface elevated 

 at irregular intervals into low monticules, the latter broad and occupied by zooecia 

 a little larger than the average. Zooecia unusually large, about eight in 3 mm., their 

 apertures polygonal, the walls thin, with one or two small acanthopores to each 

 zooecium rising generally from the wall at some point between the angles of junction. 

 Many of the latter are occupied by small mesopores, but these are to be regarded aa 

 comparatively very few and at all times diflBcult to distinguish externally. 



