LIST OF ILLUSTRATIONS. XIH 



Page. 

 Fig. 92. Fenestella striolata. a, zoarium, natural size; h, nonporiferous side 

 enlarged; c, small portion of poriferous side, enlarged. (After 

 Eichwald .) 175 



93. Monticulipora arborea bispinulata. a, one of the type-specimens, 



natural size, incrusting abrachiopod fragment; 6 and c, tangential 

 section, X 20, and a portion, X 30; cZ and e, a vertical section, 

 X20andX30 180 



94. Monticulipora dagoensis. a, tangential section, X 20; 6, portion of 



same, X 35; c, vertical section, X 20 181 



95. Orbignyella germana. a, the type-specimen, natural size; 6, view 



of the usual characters seen in tangential section, X 20 ; c, tangen- 

 tial section, X 20; d, portion of the same, X 35; e, vertical section, 

 X 20, with acanthopores little developed; /, another vertical sec- 

 tion, X 20 182 



96. Orbignyella expansa baltica. a, tangential section, X 20; 6, several 



zocecia of the same, X 35; c, vertical section, X 10, through an 

 entire zoarial layer; d, portion of the same section, X 20 184 



97. Homotrypa similis. a, surface of a Minnesota specimen, X 18; h, 



two portions of a tangential section, X 18, c, vertical section, X 18. 

 (After Ulrich.) 186 



98. Homotrypa similis. a, fragment of a branched zoarium, natural size; 



6, tangential section, X 20; c, vertical section, X 20 186 



99. Homotrypa subramosa. a, fragment of a zoarium, natural size; 6, 



surface of an ordinary fragment, X 9; c, a tangential section, X 18; 

 d, tangential section, X 18; e, vertical section of a typical example, 

 X 18. (After Ulrich.) 188 



100. Homotrypa subramosa. a, tangential section of a Russian specimen, 



X 20; h, several zooecia of the same, X 60; c, two portions of a ver- 

 tical section, X 20 188 



101. Homotrypella instabilis. a and 6, two fragments, natural size; c, sur- 



face of a well-preserved example, X 18; d, tangential section, 

 X 18; e, another tangential section, X 18;/, small portion of a 

 tangential section, X 50; gr, vertical section, X 18. (After Ulrich.) 190 



102. Homotrypella instabilis. a, b, and c, vertical sections, X 20; d, tan- 



gential section, X 20 191 



103. Homotrypella cribrosa. a, vertical section, X 20; b, tangential sec- 



tion, X 20; c, several zooecia, X 35 193 



104. Homotrypella hospitalis crassa. Ulrich's views of Atactoporella 



crassa. a, tangential section, X 18, of the Minnesota type; b, ver- 

 tical section of the same, X 18; c, several zooecia in tangential sec- 

 tion, X 50 194 



105. Homotrypella hospitalis crassa. a, a Russian example, natural size; 



b, tangential section, X 40; c, tangential section, X 40; d, e, and/, 

 three vertical sections, X 20, illustrating the characters in various 

 parts of the zoarium 195 



106. Mesotrypa discoidea orientalis. a, b, and c, top, basal, and side 



views of a zoarium, natural size; d, tangential section, X 20; e, a 

 portion of the same, X 40; /, vertical section, X 20 197 



107. Mesotrypa egena. a, side view of type-specimen, natural size; 6, 



tangential section, X 20; c and d, portions of the same, X 35; 



e and /, two portions of a vertical section, X 20 199 



108. Mesotrypa expressa. a, side view of the type-specimen; 6, view of 



the same example fractured lengthwise; c, tangential section, 

 X 20; d,a portion of the same, X 35; e and/, two vertical sections, 

 X 20 200 



