EAELY PALEOZOIC BRYOZOA OF THE BALTIC PEOVINCES. 237 



illustrations of the Minnesota species Monotrypa cuTnulata are given 

 for comparison. 



Occurrence. — An extremely abundant species in probably all the 

 formations ranging from the Glauconite limestone (B2) to the Wesen- 

 berg limestone (E). The collections of the United States National 

 Museum contain specimens from the Glauconite limestone (B2) at 

 Tswos, on the Wolchow River, Duboviki, Gornaja Scheldicha, and 

 Pawlovsk, government of St. Petersburg; from the Orthoceras lime- 

 stone (B3) at Reval, Malla, and Port Kunda, Esthonia, and Paw- 

 lovsk, government of St. Petersburg; from the Echinospherites lime- 

 stone (Cl) at Luggenhusen, Katlino, 4 miles east of Reval, and 

 Duboviki; and from the Wesenberg limestone (E) at Wesenberg. 

 Dybowski mentions a number of other localities, such as Kuckers 

 and Jewe, which have afforded specimens. The American form was 

 found in the Lower Trenton limestone, Goodhue County, Minnesota, 

 and at Ottawa, Canada. 



Plesioty pes. —Csit. Nos. 26906, 57339 to 57350, U.S.N.M. 



Represented in British Museum by specimens from various locali- 

 ties in Russia and from the island of Oeland. 



DIANULITES GRANDIS, new species. 

 Text fig. 133. 



Zoarium massive, regularly hemispheric, consisting of numerous 

 superposed layers of zooecia. The type-specimen is 6 cm. in diam- 

 eter and about 3 cm. high. The base as usual in such forms is 

 slightly concave and is covered with a concentrically wrinkled 

 epitheca; upper surface celluliferous and smooth. The zooecia are 

 large, exceptionally thin-walled, polygonal, with distinct clusters of 

 larger size than the average at intervals of about 6 mm.; two to 

 three zooecia in 2 mm., one of the average size being 0.8 mm. in 

 diameter, while those forming the maculae are frequently over a 

 millimeter wide. Mesopores and acanthopores absent. On the 

 best preserved portions of the surface exceptionally small granules 

 may be observed on the zocecial walls. These appear to better 

 advantage in tangential sections, although even here, on account 

 of the great tenuity of the zocecial walls, they seldom are as dis- 

 tinctly marked as I have shown them in figure 133 e. Vertical 

 sections show thin, slightly crenulated walls with three or more 

 diaphragms in a tube diameter in the mature zone. Figure 13S d 

 illustrates the occurrence of several superposed zocecial layers, each 

 with its short, immature zone and a longer mature portion with 

 numerous diaphragms. 



The hemispheric zoarium, thin walls, and exceptionally large 

 zooecia are sufficient to distinguish this from all similarly growing 



