EAELY PALEOZOIC BEYOZOA OF THE BALTIC PROVHSTCES. 287 



variety of the other, an examination of the magnified surface will 

 distinguish them. The characters of EemipTiragma panderi are as 

 follows : 



Zoarium of stout, cylindrical, rather infrequently dividing branches, 

 averaging 10 mm. in diameter. Surface smooth, with conspicuous 

 maculae composed of thick-walled mesopores and zooecia larger than 

 usual or of aggregations of mesopores completely filled with a dense 

 tissue. The latter arrangement in the maculse forms the spots weU 

 shown in Dybowski's figure. These maculae are either level with the 

 surface or are slightly sunk beneath the plane of the ordinary zooecia. 

 Zooecial apertures subangular, thick walled, and exhibiting numer- 

 ous blunt acanthopores on the walls and on the closed mesopores 

 forming the maculae. Six zooecia in 2 mm. Mesopores few, seldom 

 more than one to a zocecium, and usually closed at the surface. 

 Acanthopores of medium size, but so numerous that 20 to 24 some- 

 times surround a zooecium. 



The internal structure is so distinct that a description, in addition 

 to the figures, is hardly necessary. Vertical sections show charac- 

 teristic incomplete diaphragms very distinctly. In this species cross 

 partitions of any kind are absent in the immature zone, and semi- 

 diaphragms are first inserted in the bend to the mature region. In 

 the latter region proper they are well developed both in size and 

 number. The especial features of tangential sections are the angu- 

 lar, thick-walled zooecia, the numerous acanthopores, and the scarcity 

 of mesopores. 



Occurrence. — Common in the Kuckers beds (C2) and apparently 

 rare in the Jewe limestone (Dl), Baron ToU's estate, Esthonia. 



Plesiotype.—Csit. No. 57418, U.S.N.M. 



British Museum, specimens and thin sections from the Kuckers 

 (C2), Baron Toll's estate. 



HEMIPHRAGMA GLABRUTvI, new species. 



Plate 10, fig. 1; text fig. 175, 



Zoarium ramose, of smooth, slender, cylindrical, frequently dividing 

 branches, 3 to 4 mm. in diameter. Maculae composed of tliick- 

 walled mesopores, a conspicuous feature of the surface under the 

 hand lens but less noticeable to the unaided eye. Zooecial apertures 

 subangular, thick-walled, frequently separated by mesopores with 

 walls of equal thickness. About seven zooecia in 2 mm. Acantho- 

 pores very inconspicuous or wanting. 



In the axial region of vertical sections the zocEcial tubes have 

 strongly crenuJated or fluctuating walls, and are not crossed by 

 partitions save an occasional semidiaphragm developed usually in the 

 bend to the mature zone. The zooecial walls become thicker and less 



