028 BULLETIN 92, UNITED STATES NATIONAL MUSEUM. 



PACUYDICTYA Ulrkli. Genotype: P. robusta Ulrich. 



Facliydictya Ulrich, Jour. Cincinnati Soc. Nat. Hist., 5, 1882, p. 152. Foerste, 

 Bull. Sci. Lab. Denison Univ., 2, 18S7, p. 162. Miller, N. A. Geol. Pal., 1889, 

 p. 313. Ulrich, Geol. Surv. Illinois, 8, 1890, pp. 390, 522; Geol. Minnesota, 3, 

 1893, p. 145. Pocta, Syst. Sil. Centre Boheme, 8, pt. 1, 1894, p. 15. Simp- 

 son, 14th Ann. Rep. State Geol. New York for 1894, 1897, p. 530. Nicklesand 

 Bassler, Bull. U. S. Geol. Surv., 173, 1900, p. 48. Hennig, Archiv. fur Zool., 

 K. Sven. Vet.-Akad. Stockholm, 2, No. 10, 1905, p. 25. Bassler, Bull. U. S. 

 Geol. Surv., 292, 1906, p. 57. Grabau and Shimer, N. A. Index Fossils, 1, 

 1907, p. 159. Cumings, 32d Ann. Rep. Dep. Geol. Nat. Res. Indiana, 1908, 

 p. 751. Bassler, Bull. U. S. Nat. Mus., 77, 1911, pp. 137, 138. 



Pachydictya acuta (Hall). 



Stictopora? acuta Hall, Pal. New York, 1, 1847, p. 74, pi. 26, figs. 3a-b. Billings, 

 Canadian Nat. Geol., 1, 1856, p. 317. Lesley, Geol. Surv. Pennsylvania, 

 Rep. P 4, 1890, p. 1063, figs. Ulrich, Jour. Cincinnati Soc. Nat. Hist., 5, 1882, 

 p. 168, pi. 8, figs. 1-lb. 



5?tilodictya acuta Nicholson, Pal. Province Ontario, 1875, p. 12, fig. 3. Billings, 

 Canadian Nat. Geol., 1, 1856, p. 318, fig. 5; Geol. Canada, Geol. Surv. Canada, 

 1863, p. 158, fig. 121. Emmons, Amer. Geology, 1, pt. 2, 1855, pi. 7, figs. 3a-c; 



Pachydictya acuta Ulrich, 14th Ann. Rep. Geol. Minnesota, 1886, pp. 75, 76; 

 Contr. Micro-Pal. Cambro-Sil., pt. 2, 1889, p. 44, Geol. Minnesota, 3, 1893, 

 p. 155, pi. 8, figs. 11-17; pi. 9, fig. 7. Grabau and Shimer, N. A. Index 

 Fossils, 1, 1907, p. 159. Whiteaves, Pal. Foss., 3, 1897, p. 161. 



Trenton: Trenton Falls, etc., New York; Ontario; Kentucky; Iowa; Minnesota. 

 Manitoba; etc. 



Plesiotypes.Czt. Nos. 43721, 44099, U.S.N.M. (Ulrich). 



PACHYDICTYA ALCYONE Billings. See Pachydictya crassa. 

 PACHYDICTYA ARQUTA Ulrich. See Pachydictya crassa. 



Pachydictya bifurcata (Hall). 



Eschara bifurcata Van Cleve (MS.). 



Stictopora bifurcata Hall, 12th Ann. Rep. Indiana Geol. Nat. Hist., 1883, p. 267, 

 pi. 13, figs. 3, 4. Lesley, Geol. Surv. Pennsylvania, Rep. P 4, 1890, p. 1063, 

 fig. 



Pachydictya bifurcata Foerste, Bull. Sci. Lab. Denison Univ., 2, 1887, p. 163; 

 ibid., 3, 1888, pi. 15, fig. 9; Geol. Surv. Ohio, 7, 1895, p. 599, pi. 28, fig. 9. 

 Bassler, Bull. U. S. Nat. Mus., 77, 1911, pp. 143-145, figs. 67, 68. 



Stictopora scalpellum Eichwald (not Lonsdale), LethaBa Rossica, 1, 1860, p. 390, 

 pi. 24, fig. 15a-c. 



Rhinidictya? Borkholmiensis Wiman, Bull. Geol. Inst. Univ. Upsala, 5, pt. 2, 

 1901, p. 180, pi. 6, figs. 1-7. 



Silurian: Dayton, Fairhaven, etc., Ohio; Kentucky (Brassfield); various locali- 

 ties in Esthonia, Russia (Lyckholm and Borkholm). 



Plesiotypes.C&t. No. 57240, U.S.N.M. (Bassler). 



Pachydictya bifurcata instabilis Foerste. 



Pachydictya bifurcata var. instabilis Foerste, Bull. Sci. Lab. Denison Univ., 2, 



1887, p. 164; ibid., 3, 1888, pi. 15, fig. 10; Geol. Surv. Ohio, 7, 1895, p. 599, 



pi. 28, fig. 10. 

 Upper Medinan (Brassfield): Near New Carlisle, Ohio. 



PACHYDICTYA CONCILATRIX Ulrich. See Trigonodictya conciliatrix. 



