118 



BULLETIN 11, UNITED STATES NATIONAL MUSEUM. 



Genus PH^ENOPORA HalL 



Phsenopora Hall, Amer. Joum. Sci., ser. 2, vol. 11, 1851, p. 379; Nat. Hist, 

 New York, Pal., vol. 2, 1852, p. 46. — Pictet, Traite de Paleontologie, 2d. ed., 

 vol. 4, 1857, p. 169. — Ulrich, Joum. Cincinnati Soc. Nat. Hist., vol. 5, 

 1882, p. 152.— FoERSTE, Bull. Sci. Lab. Denison Univ., vol. 2, 1887, p. 157.— 

 Miller, North. Amer. Geol. and Pal., 1889, p. 314. — Ulrich, Geol. Surv. 

 Illinois, vol. 8, 1890, p. 392; Geol. and Nat. Hist. Sxirv. Minnesota, vol. 3, 

 pt. 1, 1893, p. 173.— PocTA, Syst. Sil. Center Boheme, vol. 8, pt. 1, 1894, 

 p. 8.— Ulrich, Zittel's Textbook of Paleontology (Eng. ed.), 1896, p. 279.— 

 Simpson, Fourteenth Ann. Rep. State Geologist New York for the Year 1894, 

 1897, p. 541.— NicKLES and Bassler, Bull. 173, U. S. Geol. Surv., 1900, p. 

 46. — Hennig, Archiv. fur Zool., K. Sven. Vet.-Akad. Stockholm, vol. 2, 

 No. 10, 1905, p. 10.— Bassler, Bull. 292, U. S. Geol. Surv., 1906, p. 55. 



Like Ptilodictya and Escharopora, except that there are two meso- 

 pores in each interspace between the ends of the apertures. 



Genotype. — Phsenopora explanata Hall. Silurian (Clinton) of 

 Canada. 



PHiENOPORA ENSIFORMIS Hall. 



Text fig. 45. 



Phsenopora ensiformis Hall, Nat. Hist. New York, Pal., vol. 2, 1852, p. 48, pi. 18, 

 figs. 8 a-c. — Nicholson and Hinde, Canadian Journal, new ser., vol. 14, 

 1874, p. 142. — Nicholson, Pal. Province Ontario, 1875, p. 45, figs. 19, 2, 

 2a. — Ulrich, Joum. Cincinnati Soc. Nat. Hist., vol. 5, 1882, p. 172. — 

 Foerste, Geol. Surv. Ohio, vol. 7, 1895, p. 598.— Bassler, Bull. 292, U. S. 

 Geol. Surv., 1906, p. 55, pi. 27, figs. 8, 9. 

 Phsenopora cf. ensiformis Wiman, Bull. Geol. Inst. Univ. Upsala, vol. 5, pt. 2, 

 1902, p. 180, pi. 6, figs. 25-28. 



Specimens of this species have not occurred in the collections 

 before me, but I have no reason to doubt that Wiman's provisional 

 identification can be accepted as correct. His figures certainly refer 



c^ 



Fig. 45.— PH^ffiNOPORA ensiformis. Wiman's illusteations of the Boekholm foem of this sPEcaEs; 

 a AND 6, TWO small zoaeia, natural size; c, surface, xlO; d, transverse section, XIO. Bork- 



HOLM DRIFT, OjLE MyE, ISLAND OF GOTHLAND. 



to a form like Plisenopora ensiformis in which the two mesopores at 

 the end of the zooecia are poorly developed. The occurrence of other 

 early Silurian types, such as Hallopora elegantula and Lichenalia con- 



