LIST OF ILLUSTRATIONS. XIX 



Page. 

 Fig. 189. Dittoporacolliculata. a, tangential section of a young example, X 20, 

 showing the characteristic shape of zooecia and the larger set of 

 acanthopores; b, vertical section of the same specimen, X 20 307 



190. Dittopora colliculata. a, small portion of a tangential section, X 20, 



with the walls of the mesopores visible. The large and small set 

 of acanthopores are clearly developed; b, another tangential sec- 

 tion, X 20, with the mesopores and small ancanthopores obliter- 

 ated by the interzooecial tissue. This thin section was prepared 

 from a specimen identified by Dybowski as Trematopora pustu- 

 lifera; c, vertical section, X 20, showing the occurrence of semi- 

 diaphragms only in the bend to the mature zone 308 



191. Monotrypa jewensis. a, profile view of a small zoarium, natural size; 



b, surface of the same specimen, X 10; c, vertical section, X 8, 

 illustrating the crinkled walls and few diaphragms; d, portion of the 

 same section, X 20; e, tangential section, X 20, cutting a macula; 

 /, another tangential section, X 20, with numerous young zooecia 

 resembling mesopores 311 



192. Diplotrypa petropolitana. Nicholson's illustrations of Monticulipora 



(Diplotrypa) petropolitana, introduced for comparison, a, profile 

 view of an average specimen, natural size; b, basal view of same 

 showing wrinkled epitheca; c, tangential section, X 20; d, vertical 

 section through an immature and a mature zone, X 20 313 



193. Diplotrypa petropolitana. a, tangential section, X 20; 6, a portion 



of the same, X 35; c, vertical section, X 8; d and e, portions of 



a vertical section, X 20 314 



194. Diplotrypa petropolitana. a, small portion of a tangential section, 



X 8; 6, parts of same section, X 20; c, vertical section, X 8; 



d, portion of same, X 20 315 



195. Diplotrypa petropolitana. a, vertical section, X 8; 6, portion of the 



same section, X 20; c, another portion, X 20; d, vertical section, 



X 20, through a macula; e, a tangential section, X 20 316 



196. Diplotrypa bicomis. a, an example natural size; b, and c, two views 



of the surface, enlarged. Copied from Eichwald's figures of Cerio- 

 pora bicomis 317 



197. Diplotrypa bicomis. a, vertical section, X 20; b, small portion of 



the same section enlarged; c, a tangential section, X 20 318 



198. Diplotrypa bicornis. a, tangential section, X 20; b, part of the same 



section, X 40; c, vertical section, X 20; d, vertical section, X 40. . 319 



199. Diplotrypa moniliformis, a, side view of a zoarium, natural size; 



b, tangential section, X 20; c, vertical section, X 8; d, portion of 



the same section, X 20 321 



200. Diplotrypa hennigi. a, side view of a zoarium, natural size; b, 



tangential section, X 20; c, vertical section, X 20 322 



201. Diplotrypa westoni. a and b, side and basal views of a zoarium, 



natm-al size; c, tangential section, X 8; through a macula and 

 adjoining zooecia; d, portion of the same section, X 20; e, vertical 

 section, X8; cutting a macula; /, several tubes of the same, X 20. . 324 



202. Hallopora multitabulata. a, view of typical specimen, natural size; 



6, surface of the same, X 9; c, surface of a finely preserved exam- 

 ple, X 18; d, vertical section, X 9 326 



203. Hallopora goodhuensis. a and b, two fragments of natural size; 



c, surface of a specimen, X 9; d, axial region of a transverse sec- 

 tion, X 18. (After Ubich.) 327 



