EAELiY PALEOZOIC BRYOZOA OP THE BALTIC PROVINCES. 273 



Internal characters.- — In tangential sections the tubes are polygonal and have rather 

 thin walls, in which the line of contact between adjoining tubes is distinctly preserved. 

 Mesopores few, small, chiefly at the angles of junction. Acanthopores small, incon- 



FiG. 161.— Batostoma magnopora. a, small specimen of nattiral size; &, tangential section, X18; 



C, PART OF AXIAL REGION IN TRANSVERSE SECTION, X18; d, VERTICAL SECTION OF ZOARIUM WITH A NAR- 

 ROW MATURE ZONE, X9. BlACK RiVEB (DECOBAH) SHALE, MINNEAPOLIS AND ST. PAXJL, MINNESOTA. 



(Aftek Uleich.) 



Fig. 162. — Batostoma magnopora. a, a small Russian example referred to the species, natural 



size; 6, TANGENTLAL section of same SPECIMEN, X20; C AND d, VERTICAL SECTION, XIO, AND A PORTION, 

 X20. WASSALEM BEDS (D3), UXNORM, EsTHONIA. 



spicuous. In vertical sections the tubes proceed toward the surface in a very gentle 

 curve until they enter the unusually narrow peripheral region, where the curve is 

 sufficiently accelerated to enable them to open at the surface with nearly direct 



