X LIST OF ILLUSTRATIONS. 



Page. 

 Fig. 45. Phsenopora ensiformis. Wiman's illustrations of the Borkholm form 

 of this species; a and h, two small zoaria, natm-al size; c, surface, 

 X 10; d, transverse section, X 10. .'. 118 



46. Arthropora simplex, a, several segments in their natural position, 



Life size; h, sui'face of a well-preserved fragment, X 18; c, several 

 zooecial apertures of the same, X 35; d, tangential section, X 18; 

 e, vertical section, X 18 120 



47. Graptodictya perelegans. a, tangential section, X 20, of the type- 



specimen; h, several zooecia, X 40; c, vertical section, X 20; d, 

 transverse section, X 20 121 



48. Graptodictya bonnemai. a, portion of a zoarium, natural size; 6, 



tangential section, X 20; c and d, several zooecia of the same, X 40, 

 with one still finther enlarged, X 60; e, vertical section, X 20 123 



49. Graptodictya proava. a, Eichwald's view -of the type-specimen of 



his Coscinium proavum, natural size; h, tangential section of 

 Hall's type of Clathropora flabellata, X 30 124 



50. Graptodictya proava. a, tangential section, X 20, cutting the stri- 



ated edge of a branch and the adjoining zooecia; h, portion of the 

 same, X 40; c, vertical section, X 20 125 



51. Graptodictya obliqua. a, the type-specimen, natmral size; 6, tangen- 



tial section, X 20; c, vertical section, X 20 126 



52. Stictoporella cribrosa. a, nearly complete zoarium natural size; 



h and c, surface of a specimen with numerous mesopores, X 9 and 

 a portion X 18; d, vertical section, X 18; e, tangential section of an 

 average specimen, X 18 128 



53. Stictoporella cribrosa. a and 6, tangential and vertical sections, X 



24, of a well developed Russian example 129 



54. Stictoporella gracilis, a, Eichwald 's original figure (Eschara gi-acilis) ; 



h and c, copies of Eichwald's illustrations of Micropora gracilis; h, a 

 zoarium, natural size, and c, surface of same, enlarged 130 



55. Stictoporella gracilis, a, tangential section, X 20; h, vertical sec- 



tion, X 20 131 



56. Rhinidictya mutabilis. a, a young specimen, described as variety 



minor, natural size; 6, the usual mature specimen; c, sm'face view, 

 X 9, of a young example; d, several apertures of the same, X 35; 

 e, surface of original of figure 6, X 9. (After UMch.) 132 



57. Rhinidictya exserta. a and h, two typical fragments, natural size; 



c, tangential section, X 20, through mature zone of an old example; 



d, vertical section, X 20, of the same specimen 133 



58. Rhinidictya exserta. a, Eichwald's original view of this species; 



h, view of his second specimen 134 



59. Phyllodictya flabellaris. a, vertical section, X 20, showing the long, 



zooecial tubes; h, minute structure of the interzooecial spaces, X 

 60; c, tangential section, X 20, with portion of a macula and adjoin- 

 ing zooecia; d, several zooecia of the same section, X 35 135 



60. Phyllodictya varia. a, portion of a large zoarium, natural size; h, 



h'agment with subparallel margins, natural size; c, surface of the 

 same, X 9; <?, two rows of apertures, X 18; e, surface of an old zoa- 

 rium, X 9; /, vertical section, X 18; 5^, tangential section, X 18. . 137 



61. Pachydictya elegans. a, tangential section, X 18; &, a single zooe- 



cium of the same section, X 35; c, transverse section, X 18, Pachy- 

 dictya foliata, showing the median tubuli distinctly 138 



