EAELY PALEOZOIC BEYOZOA OP THE BALTIC PROVINCES. 169 



Genus CHASMATOPORA Eiehwald. 



Chasmatopora Eichwald, Lethsea Rossica, vol. 1, 1860, p. 370. 



Phylloporina (Ulrich) Foerste, Bull. Scl. Lab. Denison University, vol. 2, 1887, 

 p. 150.— Ulrich, Geol. Sm-v. Illinois, vol. 8, 1890, pp. 399, 639; Geol. and 

 Nat. Hist. Surv. Minnesota, vol. 3, pt. 1, 1893, p. 208; Zittel's Textbook 

 of Paleontology (Eng. ed.), 1896, p. 283.— Nickles and Bassler, Bull. 173, 

 U. S. Geol. Surv., 1900, p. 37.— Bassler, Bull. 292, U. S. Geol. Surv., 1906, 

 p. 48. 



Subretepora D'Orbigny, Prodr. de Pal., vol. 1, 1850, p. 22. — Miller, North 

 Amer. Geol. and Pal., 1889, p. 326. 



Intricaria Hall, Nat. Hist. New York, Pal., vol. 1, 1847, p. 77. — Miller and 

 Dyer, Contr. Pal., No. 2, 1878, p. 7. 



The generic type to which this name was first appHed was best 

 described under the name of Phylloporina by Ulrich, but it seems, to 

 me that the earher designation Chasmatopora has the best right to rec- 

 ognition. The facts in the case are as follows: 



In 1860 Eichwald proposed the new genus Chasmatopora, giving a 

 fair description for that date, and basing the genus upon a single 

 species, C. tenella, which he compared with Hall's Retepora angulata, 

 from the Clinton group, of New York. His figure of C tenella, although 

 far from present standards, is sufficient to show that his type-specimen 

 was an angular meshed form closely related to Hall's species. Col- 

 lections from the Borkholm limestone show numerous examples of 

 such a species, and I have little doubt that this is the form Eichwald 

 had in mind. 



D'Orbigny's Subretepora was based upon the well-known, widely 

 distributed form Intricaria reticulata Hall, but the author of this 

 generic name relied upon Hall's faulty descriptions and figures for 

 his definition. The result was that Subretepora was incorrectly 

 defined, and for that reason Ulrich proposed the new name Phyl- 

 loporina. 



As pointed out by Ulrich, several distinct types of structm-e are 

 included in Phylloporina. It is therefore probable that with more 

 study both Phylloporina and Chasmatopora may be recognized. 



In Chasmatopora the zoarium is of irregularly anastomosing 

 branches with two to eight rows of apertures on one side and the 

 other side noncelluliferous but striated. 



Genotype. — Chasmatopora tenella Eichwald. Earliest Silurian of 

 Russia. 



CHASMATOPORA TENELLA (Eichwald). 



Text fig. 85. 



Retepora tenella Eichwald, Scbichtensyst. von Esthland, p. 207; Urwelt Russ- 



lands, vol. 2, 1842, p. 47, pi. 1, fig. 7. 

 Chasmatopora tenella Eichwald, Bull, de la Soc. Nat. Moscou, 1855, No. 4, p. 460; 



Letbsea Rossica, vol. 1, 1860, p. 371. 

 Cfr. Retepora angulata Hall, Nat. Hist. New York, Pal., vol. 2, 1852, p. 49, pi. 



19, figs. 3a-h. 



