152 



large zoa'cia and niesopores, elevated above, or depressed slightly below 

 the general level of the surface. About '.) niaeulje in 1 S(i. cm. Mesopores 

 abundant at the surface, frecpieutly entirely surroinidiiig the zoa'cia ; at 

 other times not conspicuous. Zo(ecial ai>ertures round, and regular in size. 

 Acauthopores. in unweatliered specimens, appearing at the surface as 

 large blunt spines at the angles of the zocecia, and giving tu the surface 

 a decidedly spinose appearance. The zocecia average 7 in 2 mm. 



In tangential .sections the zocecia are thick-walled and round. The 

 angles bebveen the zocecia are filled with secondary sclerenchynia and 

 acanthopores. IMesopores usually abundant, but nearly absent in some sec- 

 tions. Acanthopores numerous, 4 to 10 surrounding a zooecium ; large and 

 thick-walled, with a small distinct central canal; sometimes indenting the 

 zooecial walls. No hitei'mural lamina. Communication pores usually ab- 

 sent, but numerous in some sections. 



In longitudinal sections the zocecia are thin-walled and wavy in the 

 axixal region, and usually without diaphragms. Diaphragms begin ab- 

 ruptly as the mature region is entered, and become numerous toward the 

 surface, where they are from one-half to one tube-diameter apart. Zooecial 

 walls much thickened in the mature region, and proceeding directly to 

 the surface, where they emerge at right angles to the latter. In immature 

 specimens the zocecial apertures are oval, the mature region shallow, and 

 the zocecia emerge obliquely to the surface. In the longitudinal section 

 the acanthopores are thick-walled, with a small central canal, crossed by 

 an occasional diaphragm. The diaphragms in the zocecia are usually 

 straight, but are occasionally cystoid. Diai)hragms are more numerous in 

 the mesopores. 



The distinguishing features of Batostoma prosscri are the ramose 

 growth, numerous mesopores and large acanthoi>ores. The species is named 

 in honor of Professor C. S. I'ros.ser of Ohio State University. It occurs 

 in the upper 40 feet of the Waynesville, and commonly in the lower 20 

 feet of the Liberty, at Wei«burg, Indiana. It disappears abruptly at the 

 level of the I'Icctavihonites scrircus- layer, as dot^s also B. r(i)iavs, with 

 which it is as.sociated. 



