EARLY PALEOZOIC BEYOZOA OP THE BALTIC PEOVINCES. 



137 



Occurrence. — Tlie American types of tliis species seem to he 

 limited to the Rliinidictya bed of the Black River (Decorah) shales of 

 Minnesota. The Russian examples studied were found in the Was- 

 salem beds (D3) at Uxnorm (Cat. No. 57233, U.S.N.M.). 



British Museum, one specimen from the Wassalem beds at Ux- 

 norm. 



Fig. 60.— Phyllodictya vaeia. a, poetion of a large zoaritjm, natural size; 6, fragment -with sub- 

 parallel margins, NATURAL size; C, SURFACE OF THE SAME, X9; d, TWO ROWS OF APERTURES, Xl8, 

 SHOWING THE PAPILLOSE CHARACTER OF THE RIDGES; e, SURFACE OF AN OLD ZOARIUM, X9, EXHIBITING 

 DISTINCT MACUL.E; /, VERTICAL SECTION, X18; Q, TANGENTL4L SECTION, Xl?- BLACK RiVER (DEGORAH) 



SHALES, Minneapolis, Minnesota. (After Ulrich.) 



Genus PACHYDICTYA Ulrich. 



Pachydictya Ulrich, Journ. Cincinnati Soc. Nat. Hist., vol. 5, 1882, p. 152. — 

 FoERSTE, Bull. Sci. Lab. DenisonUniv., vol. 2, 1887, p. 162. — Miller, North 

 Amer. Geol. and Pal., 1889, p. 313. — Ulrich, Geol. Surv. Illinois, vol. 8, 

 1890, pp. 390, 522; Geol. and Nat. Hist. Surv. Minnesota, vol. 3, pt. 1, 1893, 

 p. 145. — Simpson, Fourteenth Ann. Rep. State Geologist of New York for 

 the year 1894, 1897, p. 530.— NiCKLES~and Bassler, Bull. 173, U. S. Geol. 

 Surv., 1900, p. 48y— Bassler, Bull. 292, U. S. Geol. Surv., 1906, p. 57.— 

 Hbnnig, Archiv fur ZooL, K. Sven. Vet.-Akad. Stockholm, vol. 2, No. 10, 

 1905, p. 25. — CuMiNGS, Thirty-second Ann. Rep. Dep. Geol. Nat. Res. In- 

 diana, 1907, p.»751. 



All of the four species of Pachydictya found in the Baltic strata 

 prove to belong to that section of the genus in which the zoarium is 



