EAELY PALEOZOIC BEYOZOA OF THE BALTIC PROVINCES. 249 



large size of the mesopores is evident in figures 142 a-c. The acan- 

 thopore is so large that its minute structure is very clear. Sections 

 cutting across the acanthopore show a rounded structure of concen- 

 tric rings with a central clear space. In vertical sections the con- 

 centric rings are seen to be the cut edges of cones of tissue arranged 

 upon each other. Each of these cones has its apex truncated, and, as 

 ■a result, a tube passes through the midlength of the acanthopore. 

 In tangential section this tube is represented by the central clear 

 space. Diaphragms are rather frequent in the immature zone of the 

 zooecia but few in the mature region. The mesopores are rather 

 closely tabulated throughout. 



The exceptionally large acanthopores will distinguish this from 

 all other ramose bryozoans. Lioclemella clava has a somewhat 

 similar zooecial structure, but has smaller and more numerous 

 acanthopores as v/ell as a different growth habit. 



Occurrence. — Not uncommon in the Orthoceras limestone (B3) on 

 the island of Rogo, near Baltischport (Cat. No. 57322, U.S.N.M.); 

 in the Echinospherites limestone (Cl), 4 miles east of Reval (Cat. 

 No. 57323, U.S.N.M.); and in the Kuckers shale (C2), Baron Toll's 

 estate, near Jewe (Cat. No. 57324, U.S.N.M.), Esthonia. Rare in 

 the Chasmops limestone, south of Bodahamn, island of Oeland. 



Holotype.— Cat. No. 57322, U.S.N.M. 



British Museum, thin sections of the type-specimen, and specimens 

 from other localities in Russia. 



Genus LIOCLEMELLA Foerste. 



Lioclemella Foerste, Geol. Surv. Ohio, vol. 7, 1895, p. 600. — NicKLEsand Bassler 

 Bull. 173, U. S. Geol. Surv., 1900, p. 33.— IJLRicHand Bassler, Smiths. Misc. 

 Coll., vol. 47, 1904, p. 39.— Bassler, Bull. 292, U. S. Geol. Surv., 1906, p. 36. 



Species of this genus may be readily recognized by their club- 

 shaped or sparsely divided branches pointed at the distal end for 

 articulation with an attached expanded base. In zooecial structure 

 the genus is so closely related to Lioclema that it is difficult to indicate 

 any distinguishing characters. Species with such a jointed zoarium 

 are not uncommon in the earliest Silurian (Richmond) strata of 

 North. America, and continue, although less abundant, into the 

 Silurian. There is httle doubt that the following new species is an 

 unequivocal member of the genus. 



Genotype. — Callopora oMoensis Foerste. Silurian (Clinton) of the 

 Ohio Valley. 



LIOCLEMELLA CLAVA, new species. 

 Text fig. 143. 



Zoarium of cylindrical, slightly curved, unbranched club-shaped 

 stems, 6 mm. in diameter and about 60 mm. long, pointed at the 

 lower portion for articulation with an attached, expanded base, and 



